Difference between revision 1 and current revision
No diff available.i think when you are doing arithmetic in the integers mod something, it's not just the case that you can always do what you do in the normal numbers, rather i think that working with the negative numbers is different, in particular, division is different with them (is multiplication different too?).
Eg if you are mod 6, normally you can say "-2/2 = -1", but here, -2 = 6 - 2 = 4, so -2/2 = 4/2 = 2, and -1 = 6 - 1 = 5, and 2 != 5 mod 6.
i haven't checked this with others.
also i think the quadratic formula doesn't work if the modulus is even: http://math.stackexchange.com/a/261901/92670