Prime combinatorics - I think every programmer independently discovers the technique. You can also determine if a shorter word can be made from a longer word,

Prime combinatorics - I think every programmer independently discovers the technique. You can also determine if a shorter word can be made from a longer word, e.g. "cat" from "catch", by looking for modulo results. And the technique of Prime Combinatorics for an "alphabet" can be used to solve Poker hands, Blackjack hands, Match 3 puzzle games, slot machine reel positions, and a slew of other similar problems where you would ordinarily have to build a very complex logic table/switch-case/if-then-else decision tree.