Worth mentioning that this technique works well on any data subject area where there is a defined set of answers.

For example, permutation/combination figures, significance tables.

I was quite proud of coming up with efficient formulae for handling nPr, nCr stuff in http://www.sqlservercentral.com/articles/Troubleshooting/75990/ but suffered the DOH! moment when someone pointed out I could actually store the values in a table instead!