This will get you the results you're looking for in the OP...
Based on the original data, I don't see a need to screw with that group number thing if...

Here's one that'll appeal to any manager... MONEY!
Most cloud based providers charge based on a combination the following: 1. number of CPU ticks 2. the amount of memory used...

Yea... There's no reason to use loops or cursors to do something like this. The performance of that would be horrible.

Your best best is to simply create an...

If the potential for collisions is an absolute deal breaker. Computing the checksums separately and then concatenating them should make it damned near (if not completely) impossible to get a...

Here's another option that actually uses the loan number and date as a part of a calculation.
It's efficient enough to be calculated on the fly or it could be...