Hash Compression
It can be very useful to compress a hash value so that it becomes smaller, there are some methods to achieve this:
# The division method
In order to compress a hash i in the range $[0, N-1]$ you can simply calculate:
$$ i mod N $$
# The MAD method
MAD is more sophisticated then the division method since it eliminates repreated patters in a set of integers.
$$ [(ai+b) mod p] mod N $$
Where $p$ is a prime number greater than $N$ and $a$ and $b$ are randomly selected integers.