3.5.1 Division Method
h(k) = k mod m
A key is mapped into one of m slots using the function
Requires only a single division, hence fast
m should not be :
a power of 2, since if m = 2p, then h(k)
is just the p lowest order bits of k
a power of 10, since then the hash function does not depend on all the
decimal digits of k
2p - 1. If k is a character string interpreted in radix
2p, two strings that are identical except for a transposition
of two adjacent characters will hash to the same value.
Good values for m
primes not too close to exact powers of 2.