FactorMan app for iPhone and iPad

This math game is played against the superhero FactorMan! You earn points by choosing numbers between 1 and 100. If you choose 5, you get 5 points; if you choose 18, you get 18 points. But FactorMan gets the sum of all of the factors of the number you have chosen (except for the number itself). If you choose 12, for example, you get 12 points, but FactorMan gets 1+2+3+4+6=16 points! Once a number has been used to gain points (by either you or FactorMan), it cannot be used again, and you may choose only numbers that have at least one other factor left on the board. To win you must have good arithmetic skills and develop a careful strategy. It is not as easy as it might sound! You can also play the game with a human opponent instead of FactorMan. This significantly changes the strategy needed to win.