The game is very simple and tends to make fun out of practicing basic math calculations.

Rules:
At the beginning the two random numbers appears on the board. Player and opponent choose two of them and make subtractions by turn. The one who is unable to make a move loses the game.
"Hint" button allows to find out the number of the next move by solving simple math equation or answering on question.
"You start" button gives a privilege of first move to the opponent. Do so, if you calculated or guessed that making a first move will result to the lost of the game.
"Reset" button simply reset current game.

Screenshots: