Comment by blikdak

Yes. Try adding 1 to a number which is already (in binary) all '1's. If you don't know the size of a byte, or an 'int' or a 'long int' etc for the language you are using you will be mystified why it is now 0, or maybe some other number your language decided was sensible to use (signed vs. unsigned etc). Then extrapolate that times 100 when dealing with floating point etc and presenting a sensible total in your shopping cart web app. If you don't know this stuff learn it or stay away from programming.