I am looking for a mathematical function which can duplicate what the MOD function can do in Visual Basic. Basically I want to a function which on supplying two numbewrs will return just the remainder as an integer. Such that:

17 / 3 = 5 r2
(3 * 5) + 2 = 17
2 = 17 - (3 * 5)

a = Integer Part Of Answer
d = Denominator
n = Numerator
r = Remainder

r = n - (a * d)

Does anyone have any ideas?