It depends on how you define the modulo operator [0]--there are definitions where (-1)%5 == 4 and definitions where (-1)%5 == -1. Presumably the GP is referring

It depends on how you define the modulo operator [0]--there are definitions where (-1)%5 == 4 and definitions where (-1)%5 == -1. Presumably the GP is referring to the former case. [0]: https://en.wikipedia.org/wiki/Modulo_operation#Remainder_calculation_for_the_modulo_operation https://en.wikipedia.org/wiki/Modulo_operation#Remainder_cal...