On Oct 7, 2012, at 6:49 PM, Esteban Izaguirre <esteban...@gmail.com> wrote:
> Hi, I'm following coursera's learn to program: the fundamentals, which > teaches programming basics in python. Our first assignement involves the > modulo operator with a negative divident, and while I've managed to get to > understand it enough for the purposes of the assignement with help from othe > rstudents, I still don't know how the hell it works, I wouldn't know how to > use modulo in another situation if it ever arised. So, i undertand how modulo > works when only positive numbers are used, but how does modulo determine, > that, say -15 % 14 is equal to 13? Or -20 % 100 is 20? I just don't get how > modulo works, all explanations I've found online only seem to be in relation > of how this applies to perl or something, can someone explain it to me? > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor After reading all the other (good) answers, let me try one other way to think about it. First, for positive integers consider 15/12 = 1 and 15%12 = 3. So 12 * (15/12) + 15%12 = 15 and we are back where we started. In order to be able to perform the same operations on a negative dividend, it has to work the way you find puzzling. Consider: -15/12 = -2 and -15%12 = 9, which is the way it has to be in order for 12 * (-15/12) i.e. -24 plus -15%12 i.e. 9 to equal -15. -Bill _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
