The crossword solution for the term 'When Doubled, A Number Puzzle' is KEN, which is a three letter word. KenKen is a type of number puzzle that requires players to fill in a grid with numbers while following certain rules. The goal is to make sure that each row and column contains the numbers 1-n, where n is the size of the grid. KenKen puzzles can be played with different sizes of grids, and the difficulty increases as the size increases.