How to uniformly project a hash to a fixed number of buckets

Question

Hi Fellow Statisticians,

I have a source generating hashes (e.g. computing a string with a timestamp and other information and hashing with md5) and I want to project it into a fixed number of buckets (say 100).

sample hash: 0fb916f0b174c66fd35ef078d861a367

What I thought at first was to use only the first character of the hash to choose a bucket, but this leads to a wildly non-uniform projection (i.e. some letters apppear very rarely and other very frequently)

Then, I tried to convert this hexa string into an integer using the sum of the char values, then take the modulo to choose a bucket:

import sys

for line in sys.stdin:
    i = 0
    for c in line:
        i += ord(c)
    print i%100

It seems to work in practice, but I don't know if there are any common sense or theoretical results that could explain why and to which extent this is true ?

[Edit] After some thought I came to the following conclusion: In theory you can convert the hash into a (very big) integer by interpreting it as a number : i = h[0] + 16*h[1]+16*16*h[2] ... + 16^31*h[31] (each letter represents an hexadecimal number). Then you could modulo this big number to project it to the bucket space. [/Edit]

Thanks !