For purposes of the problem, letZ=the set of all integers. Here goes:

"Definef:ZxZ-->Zby f(n,m)=nm"

I foundfto NOT be 1-to-1. Now I need to determine whether or not it is onto (i.e. ran(f)=Z). If it is not onto I need to determine the range. I have an inkling it is onto but I have no idea to show that (nor how to determine the range!)

Please help! And Thank You!