diff --git a/res/layout/calc_eight_digit_button.xml b/res/layout/calc_eight_digit_button.xml
index 635a3918..2b2e3877 100644
--- a/res/layout/calc_eight_digit_button.xml
+++ b/res/layout/calc_eight_digit_button.xml
@@ -10,7 +10,7 @@
 													   xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
 													   a:id="@+id/eightDigitButton" a:text="8"
 													   calc:textUp="ln"
-													   calc:textLeft="0b:"
+													   calc:textLeft="0o:"
 													   calc:textDown="lg"
 													   calc:directionTextScale="0.5;0.5;0.5;0.33"
 													   style="?digitButtonStyle"
diff --git a/res/layout/calc_nine_digit_button.xml b/res/layout/calc_nine_digit_button.xml
index 86027e41..c178a105 100644
--- a/res/layout/calc_nine_digit_button.xml
+++ b/res/layout/calc_nine_digit_button.xml
@@ -10,7 +10,7 @@
 													   xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
 													   a:id="@+id/nineDigitButton" a:text="9"
 													   calc:textDown="e"
-													   calc:textLeft="0o:"
+													   calc:textLeft="0x:"
 													   calc:textUp="π"
 													   calc:directionTextScale="0.5;0.5;0.5;0.33"
 													   style="?digitButtonStyle"
diff --git a/res/layout/calc_seven_digit_button.xml b/res/layout/calc_seven_digit_button.xml
index c61ee349..c923e3a5 100644
--- a/res/layout/calc_seven_digit_button.xml
+++ b/res/layout/calc_seven_digit_button.xml
@@ -10,7 +10,7 @@
 													   xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
 													   a:id="@+id/sevenDigitButton" a:text="7"
 													   calc:textUp="i"
-													   calc:textLeft="0x:"
+													   calc:textLeft="0b:"
 													   calc:textDown="!"
 													   calc:directionTextScale="0.5;0.5;0.5;0.33"
 													   style="?digitButtonStyle"
diff --git a/res/values-ru/strings.xml b/res/values-ru/strings.xml
index ef290653..30621e55 100644
--- a/res/values-ru/strings.xml
+++ b/res/values-ru/strings.xml
@@ -183,6 +183,7 @@
 	<string name="c_op_description_integral_ab">Интегрирует функцию \'f(x)\' по переменной \'x\' от \'a\' до \'b\'.</string>
 
 	<string name="c_pf_description_factorial">Возвращает факториал от предыдущего выражения.</string>
+	<string name="c_pf_description_double_factorial">Возвращает двойной факториал от предыдущего выражения.</string>
 	<string name="c_pf_description_percent" formatted="false">Возвращает процентное значение от предыдущего выражения.\nПримеры:\n
 		100 + 50% = 150\n
 		100 * 50% = 50\n
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 4e35c5be..304fe2fd 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -184,6 +184,7 @@
 	<string name="c_op_description_integral_ab">Integrates function \'f(x)\' by \'x\' variable from \'a\' to \'b\'.</string>
 
 	<string name="c_pf_description_factorial">Gives the factorial of the expression before.</string>
+	<string name="c_pf_description_double_factorial">Gives the double factorial of the expression before.</string>
 	<string name="c_pf_description_percent" formatted="false">Gives the percent value of the expression
 		before.\nExamples:\n
 		100 + 50% = 150\n
diff --git a/src/main/java/org/solovyev/android/calculator/TextHighlighter.java b/src/main/java/org/solovyev/android/calculator/TextHighlighter.java
index 799f52d7..b535bebf 100644
--- a/src/main/java/org/solovyev/android/calculator/TextHighlighter.java
+++ b/src/main/java/org/solovyev/android/calculator/TextHighlighter.java
@@ -146,6 +146,7 @@ public class TextHighlighter implements TextProcessor<TextHighlighter.Result, St
 					if (mathType.getMathType() == MathType.text || match.length() <= 1) {
 						text1.append(text.charAt(i));
 					} else {
+						text1.append(match);
 						i += match.length() - 1;
 					}
 			}
diff --git a/src/main/java/org/solovyev/android/calculator/model/AndroidPostfixFunctionsRegistry.java b/src/main/java/org/solovyev/android/calculator/model/AndroidPostfixFunctionsRegistry.java
index db1db6e4..58c0277a 100644
--- a/src/main/java/org/solovyev/android/calculator/model/AndroidPostfixFunctionsRegistry.java
+++ b/src/main/java/org/solovyev/android/calculator/model/AndroidPostfixFunctionsRegistry.java
@@ -25,6 +25,7 @@ public class AndroidPostfixFunctionsRegistry extends AndroidMathRegistryImpl<Ope
 	static {
 		substitutes.put("%", "percent");
 		substitutes.put("!", "factorial");
+		substitutes.put("!!", "double_factorial");
 		substitutes.put("°", "degree");
 	}
 
diff --git a/src/test/java/org/solovyev/android/calculator/TextHighlighterTest.java b/src/test/java/org/solovyev/android/calculator/TextHighlighterTest.java
index 8250b741..1fd99072 100644
--- a/src/test/java/org/solovyev/android/calculator/TextHighlighterTest.java
+++ b/src/test/java/org/solovyev/android/calculator/TextHighlighterTest.java
@@ -56,6 +56,7 @@ public class TextHighlighterTest {
 		Assert.assertEquals("22x", textHighlighter.process("22x").toString());
 		Assert.assertEquals("20t", textHighlighter.process("20t").toString());
 		Assert.assertEquals("20k", textHighlighter.process("20k").toString());
+		Assert.assertEquals("3!!", textHighlighter.process("3!!").toString());
 		Assert.assertEquals("2", textHighlighter.process("2").toString());
 		Assert.assertEquals("21", textHighlighter.process("21").toString());
 		Assert.assertEquals("214", textHighlighter.process("214").toString());
diff --git a/src/test/java/org/solovyev/android/calculator/model/CalculatorEngineTest.java b/src/test/java/org/solovyev/android/calculator/model/CalculatorEngineTest.java
index 8f53f753..33542532 100644
--- a/src/test/java/org/solovyev/android/calculator/model/CalculatorEngineTest.java
+++ b/src/test/java/org/solovyev/android/calculator/model/CalculatorEngineTest.java
@@ -113,7 +113,7 @@ public class CalculatorEngineTest {
 		Assert.assertEquals("2+i", cm.evaluate(JsclOperation.numeric, "2*1+√(-1)").getResult());
 		try {
 			cm.getEngine().setAngleUnits(AngleUnit.rad);
-			Assert.assertEquals("0.921+3.142i", cm.evaluate(JsclOperation.numeric, "ln(5cosh(38π√(2cos(2))))").getResult());
+			Assert.assertEquals("0.921+πi", cm.evaluate(JsclOperation.numeric, "ln(5cosh(38π√(2cos(2))))").getResult());
 			Assert.assertEquals("-3.41+3.41i", cm.evaluate(JsclOperation.numeric, "(5tan(2i)+2i)/(1-i)").getResult());
 		} finally {
 			cm.getEngine().setAngleUnits(defaultAngleUnit);
@@ -132,7 +132,7 @@ public class CalculatorEngineTest {
 		junit.framework.Assert.assertEquals("120", cm.evaluate(JsclOperation.numeric, "(2+2+1)!").getResult());
 		junit.framework.Assert.assertEquals("24", cm.evaluate(JsclOperation.numeric, "(2.0+2.0)!").getResult());
 		junit.framework.Assert.assertEquals("24", cm.evaluate(JsclOperation.numeric, "4.0!").getResult());
-		junit.framework.Assert.assertEquals("720", cm.evaluate(JsclOperation.numeric, "3!!").getResult());
+		junit.framework.Assert.assertEquals("720", cm.evaluate(JsclOperation.numeric, "(3!)!").getResult());
 		junit.framework.Assert.assertEquals("36", Expression.valueOf("3!^2").numeric().toString());
 		junit.framework.Assert.assertEquals("3", Expression.valueOf("cubic(27)").numeric().toString());
 		try {
@@ -353,7 +353,7 @@ public class CalculatorEngineTest {
 		Assert.assertEquals("11 259 375", cm.evaluate(JsclOperation.numeric, "0x:ABCDEF").getResult());
 		Assert.assertEquals("30 606 154.462", cm.evaluate(JsclOperation.numeric, "0x:ABCDEF*e").getResult());
 		Assert.assertEquals("30 606 154.462", cm.evaluate(JsclOperation.numeric, "e*0x:ABCDEF").getResult());
-		Assert.assertEquals("2.718", cm.evaluate(JsclOperation.numeric, "e*0x:ABCDEF/0x:ABCDEF").getResult());
+		Assert.assertEquals("e", cm.evaluate(JsclOperation.numeric, "e*0x:ABCDEF/0x:ABCDEF").getResult());
 		Assert.assertEquals("30 606 154.462", cm.evaluate(JsclOperation.numeric, "0x:ABCDEF*e*0x:ABCDEF/0x:ABCDEF").getResult());
 		Assert.assertEquals("30 606 154.462", cm.evaluate(JsclOperation.numeric, "c+0x:ABCDEF*e*0x:ABCDEF/0x:ABCDEF-c+0x:C-0x:C").getResult());
 		Assert.assertEquals("1 446 257 064 651.832", cm.evaluate(JsclOperation.numeric, "28*28 * sin(28) - 0b:1101 + √(28) + exp ( 28) ").getResult());