diff --git a/.~lock.rcalc-doc.odt# b/.~lock.rcalc-doc.odt#
new file mode 100644
index 0000000..7f0f6da
--- /dev/null
+++ b/.~lock.rcalc-doc.odt#
@@ -0,0 +1 @@
+,ondra,Penguin,29.09.2013 21:06,file:///home/ondra/.config/libreoffice/4;
\ No newline at end of file
diff --git a/rcalc-doc.odt b/rcalc-doc.odt
index 55ee14a..a8bfb43 100644
Binary files a/rcalc-doc.odt and b/rcalc-doc.odt differ
diff --git a/src/net/mightypork/semestralka/CalculatorBatch.java b/src/net/mightypork/calculator/CalculatorBatch.java
similarity index 97%
rename from src/net/mightypork/semestralka/CalculatorBatch.java
rename to src/net/mightypork/calculator/CalculatorBatch.java
index 9e32f9d..0b1f756 100644
--- a/src/net/mightypork/semestralka/CalculatorBatch.java
+++ b/src/net/mightypork/calculator/CalculatorBatch.java
@@ -1,4 +1,4 @@
-package net.mightypork.semestralka;
+package net.mightypork.calculator;
 
 
 import java.io.File;
@@ -19,7 +19,7 @@ import net.mightypork.rcalc.numbers.Fraction;
  */
 public class CalculatorBatch implements Runnable {
 
-	/** Rcalc Session used by the calculator */
+	/** RCalc Session used by the calculator */
 	private RCalcSession session = new RCalcSession();
 
 	/** File to load the expressions from */
diff --git a/src/net/mightypork/semestralka/CalculatorInteractive.java b/src/net/mightypork/calculator/CalculatorInteractive.java
similarity index 93%
rename from src/net/mightypork/semestralka/CalculatorInteractive.java
rename to src/net/mightypork/calculator/CalculatorInteractive.java
index 6bd82c8..4c74cf9 100644
--- a/src/net/mightypork/semestralka/CalculatorInteractive.java
+++ b/src/net/mightypork/calculator/CalculatorInteractive.java
@@ -1,4 +1,4 @@
-package net.mightypork.semestralka;
+package net.mightypork.calculator;
 
 
 import java.io.File;
@@ -17,7 +17,7 @@ import net.mightypork.rcalc.numbers.Fraction;
  */
 public class CalculatorInteractive implements Runnable {
 
-	/** Rcalc Session used by the calculator */
+	/** RCalc Session used by the calculator */
 	private RCalcSession session = new RCalcSession();
 
 	/** Show results as fractions */
@@ -42,17 +42,18 @@ public class CalculatorInteractive implements Runnable {
 		 + "Commands:\n"
 		 + "\thelp - show this help\n"
 		 + "\texit - quit the calculator\n"
-		 + "\tdebug - toggle debug mode (default off)\n"
 		 + "\tdecimal - toggle decimal/fractional output\n"
 		 + "\tvars - print a list of variables\n"
+		 + "\tdebug - toggle debug mode (default off)\n"
+		 + "\tutest - perform RCalc unit tests\n"
 		 + "\tload filename - execute commands from a file\n"
 		 + "\t\t(Expressions from the file can use/change variables)\n"
 		 + "\n"
 		 + "Mathematical operations, syntax\n"
 		 + "\tSupported: + - * / % ^ ! ( )\n"
 		 + "\tMultiplication sign can be omitted where it makes sense.\n"
-		 + "\tAlong with fractions, decimal-point format works too.\n"
 		 + "\tUse 'a/b' syntax to express a fraction.\n"
+		 + "\tDecimal-point numbers are supported, too.\n"
 		 + "\n"
 		 + "Variables\n"
 		 + "\tAssign a variable:\n"
@@ -91,7 +92,7 @@ public class CalculatorInteractive implements Runnable {
 			while (!sc.hasNextLine()) {}
 
 			String expr = sc.nextLine().toLowerCase().trim();
-			
+
 			if (expr.equals("%")) { // repeat last expression
 				if (history.size() > 0) {
 					expr = history.get(history.size() - 1);
@@ -101,7 +102,10 @@ public class CalculatorInteractive implements Runnable {
 					continue;
 				}
 			}
-			
+
+
+			// can't use a switch on strings because of java 6 :(
+
 			if (expr.equals("exit")) { // quit
 				System.out.println("Exit.");
 				return;
@@ -109,6 +113,10 @@ public class CalculatorInteractive implements Runnable {
 			} else if (expr.equals("help")) { // show help
 				System.out.println(helpMessage);
 
+			} else if (expr.equals("utest")) { // show help
+				Runnable r = new Tests();
+				r.run();
+
 			} else if (expr.equals("debug")) { // toggle debug mode
 
 				if (session.isDebug()) {
diff --git a/src/net/mightypork/semestralka/Main.java b/src/net/mightypork/calculator/Main.java
similarity index 93%
rename from src/net/mightypork/semestralka/Main.java
rename to src/net/mightypork/calculator/Main.java
index b5069be..7dd5967 100644
--- a/src/net/mightypork/semestralka/Main.java
+++ b/src/net/mightypork/calculator/Main.java
@@ -1,4 +1,4 @@
-package net.mightypork.semestralka;
+package net.mightypork.calculator;
 
 
 import java.io.File;
diff --git a/src/net/mightypork/semestralka/Tests.java b/src/net/mightypork/calculator/Tests.java
similarity index 63%
rename from src/net/mightypork/semestralka/Tests.java
rename to src/net/mightypork/calculator/Tests.java
index b852435..2080c36 100644
--- a/src/net/mightypork/semestralka/Tests.java
+++ b/src/net/mightypork/calculator/Tests.java
@@ -1,4 +1,4 @@
-package net.mightypork.semestralka;
+package net.mightypork.calculator;
 
 
 import net.mightypork.rcalc.RCalc;
@@ -9,13 +9,15 @@ import net.mightypork.rcalc.RCalc;
  * 
  * @author Ondrej Hruska
  */
-public class Tests {
+public class Tests implements Runnable {
 
 	/**
 	 * Run the tests
 	 */
-	public static void run() {
+	@Override
+	public void run() {
 
+		System.out.println("--- RCalc Unit Tests ---");
 		RCalc rc = new RCalc();
 		rc.setDebug(true);
 
@@ -27,22 +29,18 @@ public class Tests {
 				"(1-1)(1--1)(1---1)(1----1)(1--+-+-+++--+-+1)(1--+-+-+-+-----1)(5*-1)", // minus, plus
 				"-(15/2)+(72*43-2)-(12+1)", // minus with parentheses
 				"+34-(--8+2*+13)", // + at beginning of scope
-				// misc
-				"23%(6/5)",
-				"53/(5-4-1)",
-				"100!",
-				"24/4/3",
-				"(10+1)(15-3)",
-				"13(55-3/12)^2",
-				"(1/2)^-2",
-				"13^(1/2)", // should fail
-				"(1/2)*(3/4)",
+				"1000!", // big factorial
+				"24/4/3", // chained division must go LTR
+				"5-4-1", // subtraction must go LTR
+				"5(10+1)(4!3)", // implicit multiplication
+				"(1/2)^-2", // inverting a fraction
 				"(1/2)/(3/4)", // compound fraction
+				"(1/2)*(3/4)", // fraction multiplication
 		};
 		//@formatter:on
 
 		for (String expr : testCases) {
-			System.out.println("\n\n###### test case begin ######");
+			System.out.println("\n\n# Test Case #");
 
 			try {
 				System.out.println("IN: " + expr);
@@ -52,5 +50,7 @@ public class Tests {
 			}
 		}
 
+		System.out.println("--- Unit Tests End ---");
+
 	}
 }
diff --git a/src/net/mightypork/rcalc/Tokenizer.java b/src/net/mightypork/rcalc/Tokenizer.java
index bc1d69d..17646ce 100644
--- a/src/net/mightypork/rcalc/Tokenizer.java
+++ b/src/net/mightypork/rcalc/Tokenizer.java
@@ -1,7 +1,6 @@
 package net.mightypork.rcalc;
 
 
-import java.math.BigInteger;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -109,11 +108,11 @@ public class Tokenizer implements IDebugable {
 		if (debug && deepDebug) System.out.println("\nNormalize sequences of '+' and '-'\n" + input);
 
 		// turn '-' to '+-' between numbers
-		input = input.replaceAll("(?<=[0-9)!])-(?=[0-9])", "+-");
+		input = input.replaceAll("(?<=[0-9)!])-(?=[0-9.])", "+-");
 		if (debug && deepDebug) System.out.println("\n'-' to '+-' between numbers\n" + input);
 
 		// convert '-' to '+-1*' in front of non-numbers
-		input = input.replaceAll("-(?=[^0-9])", "+-1*");
+		input = input.replaceAll("-(?=[^0-9.])", "+-1*");
 		if (debug && deepDebug) System.out.println("\n'-' to '+-1*' in front of non-numbers\n" + input);
 
 		// discard useless + signs
diff --git a/src/net/mightypork/rcalc/numbers/Fraction.java b/src/net/mightypork/rcalc/numbers/Fraction.java
index 9c53326..68d10bb 100644
--- a/src/net/mightypork/rcalc/numbers/Fraction.java
+++ b/src/net/mightypork/rcalc/numbers/Fraction.java
@@ -94,16 +94,29 @@ public class Fraction implements IEvaluableToken {
 	}
 
 
+	/**
+	 * Create a fraction with numerator parsed from a string, and 1 as
+	 * denominator.
+	 * 
+	 * @param number numerator as string
+	 */
 	public Fraction(String number) {
-		if(number.contains(".")) {
+
+		if (number.matches("[.][0-9]+")) {
+			number = "0" + number;
+		}
+
+		if (number.matches("-[.][0-9]+")) {
+			number = "-0" + number.substring(1);
+		}
+
+		if (number.matches("-?[0-9]+[.][0-9]+")) {
 			String[] parts = number.split("[.]");
-			try{
-				if(parts.length != 2) throw new ParseError(""); // for the catch
-				this.numerator = new BigInteger(parts[0]+parts[1]);
+			try {
+				this.numerator = new BigInteger(parts[0] + parts[1]);
 				this.denominator = BigInteger.valueOf(10).pow(parts[1].length());
 				this.simplify_ip();
-			}catch(Exception e) {
-				e.printStackTrace();
+			} catch (Exception e) {
 				throw new ParseError("Invalid number format.");
 			}
 		} else {
@@ -270,13 +283,13 @@ public class Fraction implements IEvaluableToken {
 
 		return new Fraction(numerator.divide(gcd), denominator.divide(gcd));
 	}
-	
 
 
 	/**
 	 * Simplify the fraction (in place)
 	 */
 	private void simplify_ip() {
+
 		BigInteger gcd = numerator.gcd(denominator);
 
 		numerator = numerator.divide(gcd);