diff -r 1c999569643b -r acf2c31e22d4 samples/composition/src-api2.0/api/Arithmetica.java
--- a/samples/composition/src-api2.0/api/Arithmetica.java	Sat Jun 14 10:04:51 2008 +0200
+++ b/samples/composition/src-api2.0/api/Arithmetica.java	Sat Jun 14 10:04:53 2008 +0200
@@ -24,7 +24,7 @@
     
 // BEGIN: design.composition.arith2.0
     public int sumRange(int from, int to) {
-        return (from + to) * (to - from + 1) / 2;
+        return (from + to) * (Math.abs(to - from) + 1) / 2;
     }
 // END: design.composition.arith2.0
 }