diff --git a/calculatorpp/project.properties b/calculatorpp/project.properties
index 3e8758ec..febda8cf 100644
--- a/calculatorpp/project.properties
+++ b/calculatorpp/project.properties
@@ -10,5 +10,5 @@
 # Project target.
 target=android-15
 android.library.reference.1=../calculatorpp-service
-android.library.reference.2=gen-external-apklibs/org.solovyev.android_common_0.1.2
+android.library.reference.2=gen-external-apklibs/org.solovyev.android_common_0.1.3
 
diff --git a/calculatorpp/res/layout/unit_converter.xml b/calculatorpp/res/layout/unit_converter.xml
new file mode 100644
index 00000000..5c4a3273
--- /dev/null
+++ b/calculatorpp/res/layout/unit_converter.xml
@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<LinearLayout xmlns:a="http://schemas.android.com/apk/res/android"
+              a:layout_width="fill_parent"
+              a:layout_height="fill_parent"
+              a:paddingLeft="10dp"
+              a:paddingRight="10dp"
+              a:orientation="vertical">
+
+    <LinearLayout a:layout_width="fill_parent"
+                  a:layout_height="fill_parent"
+                  a:paddingBottom="10dp"
+                  a:orientation="horizontal">
+
+        <Spinner a:id="@+id/unit_types_from"
+                 a:layout_width="wrap_content"
+                 a:layout_height="fill_parent"/>
+
+
+        <EditText a:id="@+id/units_from"
+                  a:inputType="text"
+                  a:singleLine="true"
+                  a:layout_width="fill_parent"
+                  a:layout_height="fill_parent"/>
+
+    </LinearLayout>
+
+    <LinearLayout a:layout_width="fill_parent"
+                  a:paddingBottom="10dp"
+                  a:layout_height="fill_parent"
+                  a:orientation="horizontal">
+
+        <Spinner a:id="@+id/unit_types_to"
+                 a:layout_width="wrap_content"
+                 a:layout_height="fill_parent"/>
+
+        <EditText a:id="@+id/units_to"
+                  a:editable="false"
+                  a:inputType="none"
+                  a:singleLine="true"
+                  a:layout_width="fill_parent"
+                  a:layout_height="fill_parent"/>
+
+    </LinearLayout>
+
+    <LinearLayout a:layout_width="fill_parent"
+                  a:paddingBottom="10dp"
+                  a:layout_height="fill_parent"
+                  a:gravity="center"
+                  a:orientation="horizontal">
+
+        <Button a:id="@+id/unit_converter_ok_button"
+                a:text="@android:string/ok"
+                a:paddingLeft="30dp"
+                a:paddingRight="30dp"
+                a:layout_width="wrap_content"
+                a:layout_height="wrap_content"/>
+
+        <Button a:id="@+id/unit_converter_copy_button"
+                a:text="@android:string/copy"
+                a:paddingLeft="30dp"
+                a:paddingRight="30dp"
+                a:layout_width="wrap_content"
+                a:layout_height="wrap_content"/>
+
+        <Button a:id="@+id/unit_converter_custom_button"
+                a:paddingLeft="30dp"
+                a:paddingRight="30dp"
+                a:layout_width="wrap_content"
+                a:layout_height="wrap_content"/>
+
+    </LinearLayout>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/calculatorpp/res/menu/main_menu.xml b/calculatorpp/res/menu/main_menu.xml
index fd504271..551fbc35 100644
--- a/calculatorpp/res/menu/main_menu.xml
+++ b/calculatorpp/res/menu/main_menu.xml
@@ -8,12 +8,16 @@
 	<item a:id="@+id/main_menu_item_history"
 		  a:title="@string/c_history"/>
 
+    <item a:id="@+id/main_menu_conversion_tool"
+          a:title="@string/c_conversion_tool"/>
+
 	<item a:id="@+id/main_menu_item_help"
 		  a:title="@string/c_help"/>
 
 	<item a:id="@+id/main_menu_item_about"
 		  a:title="@string/c_about"/>
 
+
 	<item a:id="@+id/main_menu_item_exit"
 		  a:title="@string/c_exit"/>
 </menu>
\ No newline at end of file
diff --git a/calculatorpp/res/values/text_strings.xml b/calculatorpp/res/values/text_strings.xml
index 55f7e189..80242e51 100644
--- a/calculatorpp/res/values/text_strings.xml
+++ b/calculatorpp/res/values/text_strings.xml
@@ -195,6 +195,7 @@
 
 	<string name="c_angle_units_changed_to">Angle units changed to \'%s\'!</string>
 	<string name="c_numeral_base_changed_to">Numeral base changed to \'%s\'!</string>
+	<string name="c_conversion_tool">Conversion tool</string>
 
 
 </resources>
\ No newline at end of file
diff --git a/calculatorpp/src/main/java/org/solovyev/android/NumeralBaseUnitType.java b/calculatorpp/src/main/java/org/solovyev/android/NumeralBaseUnitType.java
new file mode 100644
index 00000000..a0a222bf
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/NumeralBaseUnitType.java
@@ -0,0 +1,83 @@
+package org.solovyev.android;
+
+import jscl.NumeralBase;
+import org.jetbrains.annotations.NotNull;
+
+import java.math.BigInteger;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 8:00 PM
+ */
+public enum NumeralBaseUnitType implements UnitType<String> {
+
+    bin(NumeralBase.bin),
+    oct(NumeralBase.oct),
+    dec(NumeralBase.dec),
+    hex(NumeralBase.hex);
+
+    @NotNull
+    private final NumeralBase numeralBase;
+
+    private NumeralBaseUnitType(@NotNull NumeralBase numeralBase) {
+        this.numeralBase = numeralBase;
+    }
+
+    @NotNull
+    public Unit<String> createUnit(@NotNull String value) {
+        return UnitImpl.newInstance(value, this);
+    }
+
+    @NotNull
+    @Override
+    public Class<String> getUnitValueClass() {
+        return String.class;
+    }
+
+    @NotNull
+    private static final Converter converter = new Converter();
+
+    @NotNull
+    public static Converter getConverter() {
+        return converter;
+    }
+
+    public static class Converter implements UnitConverter<String> {
+
+        private Converter() {
+        }
+
+        @Override
+        public boolean isSupported(@NotNull UnitType<?> from, @NotNull UnitType<String> to) {
+            return NumeralBaseUnitType.class.isAssignableFrom(from.getClass()) && NumeralBaseUnitType.class.isAssignableFrom(to.getClass());
+        }
+
+        @NotNull
+        @Override
+        public Unit<String> convert(@NotNull Unit<?> from, @NotNull UnitType<String> toType) {
+            if (!isSupported(from.getUnitType(), toType)) {
+                throw new IllegalArgumentException("Types are not supported!");
+            }
+
+            final NumeralBaseUnitType fromType = (NumeralBaseUnitType) from.getUnitType();
+            final NumeralBase fromNumeralBase = fromType.numeralBase;
+            final NumeralBase toNumeralBase = ((NumeralBaseUnitType) toType).numeralBase;
+            final String fromValue = (String) from.getValue();
+
+            final BigInteger decBigInteger = fromNumeralBase.toBigInteger(fromValue);
+            return UnitImpl.newInstance(toNumeralBase.toString(decBigInteger), (NumeralBaseUnitType) toType);
+        }
+    }
+
+    @NotNull
+    public static NumeralBaseUnitType valueOf(@NotNull NumeralBase nb ) {
+        for (NumeralBaseUnitType numeralBaseUnitType : values()) {
+            if ( numeralBaseUnitType.numeralBase == nb ) {
+                return numeralBaseUnitType;
+            }
+        }
+
+        throw new IllegalArgumentException(nb + " is not supported numeral base!");
+    }
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/Unit.java b/calculatorpp/src/main/java/org/solovyev/android/Unit.java
new file mode 100644
index 00000000..c3a2d8a5
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/Unit.java
@@ -0,0 +1,17 @@
+package org.solovyev.android;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 7:54 PM
+ */
+public interface Unit<V> {
+
+    @NotNull
+    V getValue();
+
+    @NotNull
+    UnitType<V> getUnitType();
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/UnitConverter.java b/calculatorpp/src/main/java/org/solovyev/android/UnitConverter.java
new file mode 100644
index 00000000..51785cc7
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/UnitConverter.java
@@ -0,0 +1,42 @@
+package org.solovyev.android;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 7:53 PM
+ */
+public interface UnitConverter<T> {
+
+    boolean isSupported(@NotNull UnitType<?> from, @NotNull UnitType<T> to);
+
+    @NotNull
+    Unit<T> convert(@NotNull Unit<?> from, @NotNull UnitType<T> toType);
+
+    public static class Dummy implements UnitConverter<Object> {
+
+        @NotNull
+        private static final Dummy instance = new Dummy();
+
+        @NotNull
+        public static <T> UnitConverter<T> getInstance() {
+            return (UnitConverter<T>)instance;
+        }
+
+        private Dummy() {
+        }
+
+        @Override
+        public boolean isSupported(@NotNull UnitType<?> from, @NotNull UnitType<Object> to) {
+            return false;
+        }
+
+        @NotNull
+        @Override
+        public Unit<Object> convert(@NotNull Unit<?> from, @NotNull UnitType<Object> toType) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/UnitImpl.java b/calculatorpp/src/main/java/org/solovyev/android/UnitImpl.java
new file mode 100644
index 00000000..b1c08ef0
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/UnitImpl.java
@@ -0,0 +1,42 @@
+package org.solovyev.android;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 8:01 PM
+ */
+public class UnitImpl<V> implements Unit<V> {
+
+    @NotNull
+    private V value;
+
+    @NotNull
+    private UnitType<V> unitType;
+
+    private UnitImpl() {
+    }
+
+    @NotNull
+    public static <V> Unit<V> newInstance(@NotNull V value, @NotNull UnitType<V> unitType) {
+        final UnitImpl<V> result = new UnitImpl<V>();
+
+        result.value = value;
+        result.unitType = unitType;
+
+        return result;
+    }
+
+    @NotNull
+    @Override
+    public V getValue() {
+        return this.value;
+    }
+
+    @NotNull
+    @Override
+    public UnitType<V> getUnitType() {
+        return unitType;
+    }
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/UnitType.java b/calculatorpp/src/main/java/org/solovyev/android/UnitType.java
new file mode 100644
index 00000000..82175bdf
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/UnitType.java
@@ -0,0 +1,16 @@
+package org.solovyev.android;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 7:55 PM
+ */
+public interface UnitType<V> {
+
+    @NotNull
+    Class<V> getUnitValueClass();
+
+    boolean equals(@NotNull Object o);
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
index 3b7cdf68..c338d0bd 100644
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
@@ -36,10 +36,7 @@ import org.solovyev.android.calculator.about.CalculatorReleaseNotesActivity;
 import org.solovyev.android.calculator.history.CalculatorHistory;
 import org.solovyev.android.calculator.history.CalculatorHistoryState;
 import org.solovyev.android.calculator.model.CalculatorEngine;
-import org.solovyev.android.calculator.view.AngleUnitsButton;
-import org.solovyev.android.calculator.view.CalculatorAdditionalTitle;
-import org.solovyev.android.calculator.view.NumeralBasesButton;
-import org.solovyev.android.calculator.view.OnDragListenerVibrator;
+import org.solovyev.android.calculator.view.*;
 import org.solovyev.android.history.HistoryDragProcessor;
 import org.solovyev.android.view.ColorButton;
 import org.solovyev.android.view.drag.*;
@@ -615,6 +612,10 @@ public class CalculatorActivity extends Activity implements FontSizeAdjuster, Sh
 				CalculatorActivityLauncher.showHelp(this);
 				result = true;
 				break;
+            case R.id.main_menu_conversion_tool:
+                new NumeralBaseConverterDialog(null).show(this);
+                result = true;
+                break;
 			case R.id.main_menu_item_exit:
 				this.finish();
 				result = true;
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorDisplay.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorDisplay.java
index e6d3df76..5f034f0b 100644
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorDisplay.java
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorDisplay.java
@@ -13,15 +13,14 @@ import android.util.Log;
 import jscl.math.Generic;
 import jscl.math.function.Constant;
 import jscl.math.function.IConstant;
-import jscl.math.numeric.Numeric;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.jscl.JsclOperation;
 import org.solovyev.android.calculator.model.CalculatorEngine;
 import org.solovyev.android.calculator.model.CalculatorParseException;
 import org.solovyev.android.calculator.model.TextProcessor;
+import org.solovyev.android.calculator.view.NumeralBaseConverterDialog;
 import org.solovyev.android.calculator.view.TextHighlighter;
-import org.solovyev.android.calculator.view.UnitsConverter;
 import org.solovyev.android.menu.AMenuItem;
 import org.solovyev.android.view.AutoResizeTextView;
 import org.solovyev.common.utils.CollectionsUtils;
@@ -48,8 +47,7 @@ public class CalculatorDisplay extends AutoResizeTextView implements ICalculator
         convert(R.string.c_convert) {
             @Override
             public void doAction(@NotNull CalculatorDisplay data, @NotNull Context context) {
-                // todo serso: continue
-                new UnitsConverter();
+                new NumeralBaseConverterDialog(data.getGenericResult().toString()).show(context);
             }
 
             @Override
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorModel.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorModel.java
index 53c5a224..50bd0a76 100644
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorModel.java
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/CalculatorModel.java
@@ -394,7 +394,11 @@ public enum CalculatorModel implements CursorControl, HistoryControl<CalculatorH
                             filteredMenuItems.add(menuItem);
                         }
                     }
-                    AMenuBuilder.newInstance(activity, MenuImpl.newInstance(filteredMenuItems)).create(cd).show();
+
+                    if (!filteredMenuItems.isEmpty()) {
+                        AMenuBuilder.newInstance(activity, MenuImpl.newInstance(filteredMenuItems)).create(cd).show();
+                    }
+
                 } else {
                     final String errorMessage = cd.getErrorMessage();
                     if (errorMessage != null) {
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/view/NumeralBaseConverterDialog.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/view/NumeralBaseConverterDialog.java
new file mode 100644
index 00000000..27d66ed4
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/view/NumeralBaseConverterDialog.java
@@ -0,0 +1,105 @@
+package org.solovyev.android.calculator.view;
+
+import android.app.AlertDialog;
+import android.content.Context;
+import android.view.View;
+import android.view.WindowManager;
+import jscl.NumeralBase;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.NumeralBaseUnitType;
+import org.solovyev.android.Unit;
+import org.solovyev.android.UnitImpl;
+import org.solovyev.android.calculator.CalculatorModel;
+import org.solovyev.android.calculator.R;
+import org.solovyev.android.calculator.model.CalculatorEngine;
+import org.solovyev.android.calculator.model.CalculatorParseException;
+import org.solovyev.android.calculator.model.ToJsclTextProcessor;
+import org.solovyev.common.utils.MutableObject;
+import org.solovyev.common.utils.StringUtils;
+
+import java.util.Arrays;
+
+/**
+ * User: serso
+ * Date: 4/22/12
+ * Time: 12:20 AM
+ */
+public class NumeralBaseConverterDialog {
+
+    @Nullable
+    private String initialFromValue;
+
+    public NumeralBaseConverterDialog(String initialFromValue) {
+        this.initialFromValue = initialFromValue;
+    }
+
+    public void show(@NotNull Context context) {
+        final UnitConverterViewBuilder b = new UnitConverterViewBuilder();
+        b.setFromUnitTypes(Arrays.asList(NumeralBaseUnitType.values()));
+        b.setToUnitTypes(Arrays.asList(NumeralBaseUnitType.values()));
+
+        if (!StringUtils.isEmpty(initialFromValue)) {
+            String value = initialFromValue;
+            try {
+                value = ToJsclTextProcessor.getInstance().process(value).getExpression();
+                b.setFromValue(UnitImpl.newInstance(value, NumeralBaseUnitType.valueOf(CalculatorEngine.instance.getEngine().getNumeralBase())));
+            } catch (CalculatorParseException e) {
+                b.setFromValue(UnitImpl.newInstance(value, NumeralBaseUnitType.valueOf(CalculatorEngine.instance.getEngine().getNumeralBase())));
+            }
+        } else {
+            b.setFromValue(UnitImpl.newInstance("", NumeralBaseUnitType.valueOf(CalculatorEngine.instance.getEngine().getNumeralBase())));
+        }
+
+        b.setConverter(NumeralBaseUnitType.getConverter());
+
+        final MutableObject<AlertDialog> alertDialogHolder = new MutableObject<AlertDialog>();
+        b.setOkButtonOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                final AlertDialog alertDialog = alertDialogHolder.getObject();
+                if (alertDialog != null) {
+                    alertDialog.dismiss();
+                }
+            }
+        });
+
+        b.setCustomButtonData(new UnitConverterViewBuilder.CustomButtonData(context.getString(R.string.c_use), new UnitConverterViewBuilder.CustomButtonOnClickListener() {
+            @Override
+            public void onClick(@NotNull Unit<String> fromUnits, @NotNull Unit<String> toUnits) {
+                String toUnitsValue = toUnits.getValue();
+
+                if (!toUnits.getUnitType().equals(NumeralBaseUnitType.valueOf(CalculatorEngine.instance.getEngine().getNumeralBase()))) {
+                    for (NumeralBase nb : NumeralBase.values()) {
+                        if (NumeralBaseUnitType.valueOf(nb).equals(toUnits.getUnitType())) {
+                            toUnitsValue = nb.getJsclPrefix() + toUnitsValue;
+                            break;
+                        }
+                    }
+                }
+
+                CalculatorModel.instance.processDigitButtonAction(toUnitsValue, false);
+                final AlertDialog alertDialog = alertDialogHolder.getObject();
+                if (alertDialog != null) {
+                    alertDialog.dismiss();
+                }
+            }
+        }));
+
+        final AlertDialog.Builder alertBuilder = new AlertDialog.Builder(context);
+        alertBuilder.setView(b.build(context));
+        alertBuilder.setTitle(R.string.c_conversion_tool);
+
+        final AlertDialog alertDialog = alertBuilder.create();
+
+        final WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
+        lp.copyFrom(alertDialog.getWindow().getAttributes());
+
+        lp.width = WindowManager.LayoutParams.FILL_PARENT;
+        lp.height = WindowManager.LayoutParams.WRAP_CONTENT;
+
+        alertDialogHolder.setObject(alertDialog);
+        alertDialog.show();
+        alertDialog.getWindow().setAttributes(lp);
+    }
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitConverterViewBuilder.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitConverterViewBuilder.java
new file mode 100644
index 00000000..fc8107c1
--- /dev/null
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitConverterViewBuilder.java
@@ -0,0 +1,236 @@
+package org.solovyev.android.calculator.view;
+
+import android.app.Activity;
+import android.content.Context;
+import android.text.ClipboardManager;
+import android.text.Editable;
+import android.text.TextWatcher;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.*;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.Unit;
+import org.solovyev.android.UnitConverter;
+import org.solovyev.android.UnitImpl;
+import org.solovyev.android.UnitType;
+import org.solovyev.android.calculator.R;
+import org.solovyev.android.view.ViewBuilder;
+import org.solovyev.android.view.ViewFromLayoutBuilder;
+import org.solovyev.common.utils.StringUtils;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * User: serso
+ * Date: 4/20/12
+ * Time: 4:50 PM
+ */
+public class UnitConverterViewBuilder implements ViewBuilder<View> {
+
+    @NotNull
+    private List<? extends UnitType<String>> fromUnitTypes = Collections.emptyList();
+
+    @NotNull
+    private List<? extends UnitType<String>> toUnitTypes = Collections.emptyList();
+
+    @Nullable
+    private Unit<String> fromValue;
+
+    @NotNull
+    private UnitConverter<String> converter = UnitConverter.Dummy.getInstance();
+
+    @Nullable
+    private View.OnClickListener okButtonOnClickListener;
+
+    @Nullable
+    private CustomButtonData customButtonData;
+
+    public void setFromUnitTypes(@NotNull List<? extends UnitType<String>> fromUnitTypes) {
+        this.fromUnitTypes = fromUnitTypes;
+    }
+
+    public void setToUnitTypes(@NotNull List<? extends UnitType<String>> toUnitTypes) {
+        this.toUnitTypes = toUnitTypes;
+    }
+
+    public void setFromValue(@Nullable Unit<String> fromValue) {
+        this.fromValue = fromValue;
+    }
+
+    public void setConverter(@NotNull UnitConverter<String> converter) {
+        this.converter = converter;
+    }
+
+    public void setOkButtonOnClickListener(@Nullable View.OnClickListener okButtonOnClickListener) {
+        this.okButtonOnClickListener = okButtonOnClickListener;
+    }
+
+    public void setCustomButtonData(@Nullable CustomButtonData customButtonData) {
+        this.customButtonData = customButtonData;
+    }
+
+    @NotNull
+    @Override
+    public View build(@NotNull final Context context) {
+        final View main = ViewFromLayoutBuilder.newInstance(R.layout.unit_converter).build(context);
+
+        final Spinner fromSpinner = (Spinner) main.findViewById(R.id.unit_types_from);
+        final EditText fromEditText = (EditText) main.findViewById(R.id.units_from);
+        fromEditText.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+            }
+
+            @Override
+            public void afterTextChanged(Editable s) {
+                doConversion(main, context, UnitConverterViewBuilder.this.converter);
+            }
+        });
+
+        fillSpinner(main, context, R.id.unit_types_from, fromUnitTypes);
+        fillSpinner(main, context, R.id.unit_types_to, toUnitTypes);
+
+        if (fromValue != null) {
+            fromEditText.setText(fromValue.getValue());
+
+            int i = fromUnitTypes.indexOf(fromValue.getUnitType());
+            if ( i >= 0 ) {
+                fromSpinner.setSelection(i);
+            }
+        }
+
+        final Button copyButton = (Button) main.findViewById(R.id.unit_converter_copy_button);
+        copyButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                final EditText toEditText = (EditText) main.findViewById(R.id.units_to);
+
+                final ClipboardManager clipboard = (ClipboardManager) context.getSystemService(Activity.CLIPBOARD_SERVICE);
+                clipboard.setText(toEditText.getText().toString());
+                Toast.makeText(context, context.getText(R.string.c_result_copied), Toast.LENGTH_SHORT).show();
+            }
+        });
+
+        final Button okButton = (Button) main.findViewById(R.id.unit_converter_ok_button);
+        if ( okButtonOnClickListener == null ) {
+            ((ViewGroup) okButton.getParent()).removeView(okButton);
+        } else {
+            okButton.setOnClickListener(this.okButtonOnClickListener);
+        }
+
+        final Button customButton = (Button) main.findViewById(R.id.unit_converter_custom_button);
+        if ( customButtonData == null ) {
+            ((ViewGroup) customButton.getParent()).removeView(customButton);
+        } else {
+            customButton.setText(customButtonData.text);
+            customButton.setOnClickListener(new View.OnClickListener() {
+                @Override
+                public void onClick(View v) {
+                    customButtonData.clickListener.onClick(getFromUnit(main), getToUnit(main));
+                }
+            });
+        }
+
+
+
+        return main;
+    }
+
+    private void fillSpinner(@NotNull final View main,
+                             @NotNull final Context context,
+                             final int spinnerId,
+                             @NotNull List<? extends UnitType<String>> unitTypes) {
+        final Spinner spinner = (Spinner) main.findViewById(spinnerId);
+
+        final ArrayAdapter<UnitType<String>> adapter = new ArrayAdapter<UnitType<String>>(context, android.R.layout.simple_spinner_item);
+        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
+        for (UnitType<String> fromUnitType : unitTypes) {
+            adapter.add(fromUnitType);
+        }
+        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
+            @Override
+            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                doConversion(main, context, UnitConverterViewBuilder.this.converter);
+            }
+
+            @Override
+            public void onNothingSelected(AdapterView<?> parent) {
+            }
+        });
+        spinner.setAdapter(adapter);
+    }
+
+    private static void doConversion(@NotNull View main, @NotNull Context context, @NotNull UnitConverter<String> converter) {
+        final EditText fromEditText = (EditText) main.findViewById(R.id.units_from);
+
+        final EditText toEditText = (EditText) main.findViewById(R.id.units_to);
+
+        final String from = fromEditText.getText().toString();
+        if (StringUtils.isEmpty(from)) {
+            toEditText.setText("");
+        } else {
+            final UnitType<String> fromUnitType = getFromUnitType(main);
+            final UnitType<String> toUnitType = getToUnitType(main);
+
+            String to = null;
+            try {
+                if (converter.isSupported(fromUnitType, toUnitType)) {
+                    to = converter.convert(UnitImpl.newInstance(from, fromUnitType), toUnitType).getValue();
+                }
+            } catch (RuntimeException e) {
+                to = context.getString(R.string.c_error);
+            }
+
+            toEditText.setText(to);
+        }
+    }
+
+    @NotNull
+    private static Unit<String> getToUnit(@NotNull View main) {
+        final EditText toUnits = (EditText) main.findViewById(R.id.units_to);
+        return UnitImpl.newInstance(toUnits.getText().toString(), getToUnitType(main));
+    }
+
+    @NotNull
+    private static UnitType<String> getToUnitType(@NotNull View main) {
+        final Spinner toSpinner = (Spinner) main.findViewById(R.id.unit_types_to);
+        return (UnitType<String>) toSpinner.getSelectedItem();
+    }
+
+    @NotNull
+    private static Unit<String> getFromUnit(@NotNull View main) {
+        final EditText fromUnits = (EditText) main.findViewById(R.id.units_from);
+        return UnitImpl.newInstance(fromUnits.getText().toString(), getFromUnitType(main));
+    }
+
+    @NotNull
+    private static UnitType<String> getFromUnitType(@NotNull View main) {
+        final Spinner fromSpinner = (Spinner) main.findViewById(R.id.unit_types_from);
+        return (UnitType<String>) fromSpinner.getSelectedItem();
+    }
+
+    public static class CustomButtonData {
+
+        @NotNull
+        private String text;
+
+        @NotNull
+        private CustomButtonOnClickListener clickListener;
+
+
+        public CustomButtonData(@NotNull String text, @NotNull CustomButtonOnClickListener clickListener) {
+            this.text = text;
+            this.clickListener = clickListener;
+        }
+    }
+
+    public static interface CustomButtonOnClickListener {
+        void onClick(@NotNull Unit<String> fromUnits, @NotNull Unit<String> toUnits);
+    }
+}
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitsConverter.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitsConverter.java
deleted file mode 100644
index 64fb5eef..00000000
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitsConverter.java
+++ /dev/null
@@ -1,9 +0,0 @@
-package org.solovyev.android.calculator.view;
-
-/**
- * User: serso
- * Date: 4/20/12
- * Time: 4:50 PM
- */
-public class UnitsConverter {
-}
diff --git a/calculatorpp/src/test/java/org/solovyev/android/NumeralBaseUnitTypeTest.java b/calculatorpp/src/test/java/org/solovyev/android/NumeralBaseUnitTypeTest.java
new file mode 100644
index 00000000..e59a17ef
--- /dev/null
+++ b/calculatorpp/src/test/java/org/solovyev/android/NumeralBaseUnitTypeTest.java
@@ -0,0 +1,69 @@
+package org.solovyev.android;
+
+import junit.framework.Assert;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import java.util.Date;
+import java.util.Random;
+
+/**
+ * User: serso
+ * Date: 4/21/12
+ * Time: 8:24 PM
+ */
+public class NumeralBaseUnitTypeTest {
+
+    @NotNull
+    private final UnitConverter c = NumeralBaseUnitType.getConverter();
+
+    @Test
+    public void testIsSupported() throws Exception {
+        Assert.assertTrue(c.isSupported(NumeralBaseUnitType.bin, NumeralBaseUnitType.dec));
+    }
+
+    @Test
+    public void testConvertFromDec() throws Exception {
+
+        Assert.assertEquals("101", c.convert(NumeralBaseUnitType.dec.createUnit("5"), NumeralBaseUnitType.bin).getValue());
+        Assert.assertEquals("1", c.convert(NumeralBaseUnitType.dec.createUnit("1"), NumeralBaseUnitType.bin).getValue());
+        Assert.assertEquals("0", c.convert(NumeralBaseUnitType.dec.createUnit("0"), NumeralBaseUnitType.bin).getValue());
+        Assert.assertEquals("1111100111", c.convert(NumeralBaseUnitType.dec.createUnit("999"), NumeralBaseUnitType.bin).getValue());
+
+        Assert.assertEquals("A23", c.convert(NumeralBaseUnitType.dec.createUnit("2595"), NumeralBaseUnitType.hex).getValue());
+        Assert.assertEquals("AEE", c.convert(NumeralBaseUnitType.dec.createUnit("2798"), NumeralBaseUnitType.hex).getValue());
+        Assert.assertEquals("15", c.convert(NumeralBaseUnitType.dec.createUnit("21"), NumeralBaseUnitType.hex).getValue());
+        Assert.assertEquals("0", c.convert(NumeralBaseUnitType.dec.createUnit("0"), NumeralBaseUnitType.hex).getValue());
+        Assert.assertEquals("3E7", c.convert(NumeralBaseUnitType.dec.createUnit("999"), NumeralBaseUnitType.hex).getValue());
+
+        Assert.assertEquals("76", c.convert(NumeralBaseUnitType.dec.createUnit("62"), NumeralBaseUnitType.oct).getValue());
+        Assert.assertEquals("12", c.convert(NumeralBaseUnitType.dec.createUnit("10"), NumeralBaseUnitType.oct).getValue());
+        Assert.assertEquals("15", c.convert(NumeralBaseUnitType.dec.createUnit("13"), NumeralBaseUnitType.oct).getValue());
+        Assert.assertEquals("0", c.convert(NumeralBaseUnitType.dec.createUnit("0"), NumeralBaseUnitType.oct).getValue());
+        Assert.assertEquals("10445", c.convert(NumeralBaseUnitType.dec.createUnit("4389"), NumeralBaseUnitType.oct).getValue());
+    }
+
+    @Test
+    public void testRandomConvert() throws Exception {
+        final Random random = new Random(new Date().getTime());
+        for (int i = 0; i < 100000; i++) {
+            final String value = String.valueOf(random.nextInt());
+            Assert.assertEquals(value, convertChain(value, NumeralBaseUnitType.dec, NumeralBaseUnitType.oct, NumeralBaseUnitType.oct, NumeralBaseUnitType.bin, NumeralBaseUnitType.dec));
+            Assert.assertEquals(value, convertChain(value, NumeralBaseUnitType.dec, NumeralBaseUnitType.bin, NumeralBaseUnitType.hex, NumeralBaseUnitType.dec, NumeralBaseUnitType.dec));
+            Assert.assertEquals(value, convertChain(value, NumeralBaseUnitType.dec, NumeralBaseUnitType.dec, NumeralBaseUnitType.hex, NumeralBaseUnitType.oct, NumeralBaseUnitType.dec));
+            Assert.assertEquals(value, convertChain(value, NumeralBaseUnitType.dec, NumeralBaseUnitType.hex, NumeralBaseUnitType.bin, NumeralBaseUnitType.oct, NumeralBaseUnitType.dec));
+
+        }
+    }
+
+    @NotNull
+    private String convertChain(@NotNull String value, @NotNull NumeralBaseUnitType baseUnitType, @NotNull NumeralBaseUnitType... types) {
+        Unit<String> unit = baseUnitType.createUnit(value);
+
+        for (NumeralBaseUnitType type : types) {
+            unit = NumeralBaseUnitType.getConverter().convert(unit, type);
+        }
+
+        return unit.getValue();
+    }
+}
diff --git a/pom.xml b/pom.xml
index 7599b1a9..e86f312e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -32,7 +32,7 @@
             <dependency>
                 <groupId>org.solovyev.android</groupId>
                 <artifactId>common</artifactId>
-                <version>0.1.2</version>
+                <version>0.1.3</version>
                 <type>apklib</type>
             </dependency>