I am learning Objective-C using Stephen Kochan's excellent book "Programming in Objective-C 2.0". I am new also to Xcode. So far all my exercises have worked fine, but when I run program 7.6 FractionTest on page 153 I get the console message "Program received signal: "EXC_ARITHMETIC". The status shows that the program succeeded, but I don't see any output. Can anybody suggest what I might be doing wrong?