Isn't NSDecimalNumber supposed to be able to do base-10 arithmetic?

Question

NSDecimalNumber *minVal = [NSDecimalNumber decimalNumberWithString:@"0.0"];
NSDecimalNumber *maxVal = [NSDecimalNumber decimalNumberWithString:@"111.1"];
NSDecimalNumber *valRange = [maxVal decimalNumberBySubtracting:minVal];
CGFloat floatRange = [valRange floatValue];
NSLog(@"%f", floatRange); //prints 111.099998

Isn't NSDecimalNumber supposed to be able to do base-10 arithmetic correctly?

Answer 1

OK, just doing that CGFloat aNumber = 111.1; shows as 111.099998 in the debugger, even before any operation has been performed on it. Therefore the precision is lost right when it is assigned to the less precise data type, regardless of any arithmetic operations occurring later.