Mathmatical!
Good job finishing your game for the jam. I enjoyed it 'cuz I enjoy math. I like the inventive concept. My only nit picks would be it'd be nice if I could have used the number pad or mapped the four numbers onto four keys that were beside each other. I often lost my place on the top row numbers of the keyboard. Also, i felt like the bullets could have travelled a little faster. I'd move my mouse, but the bullet stream would lag behind a little too slowly.
Overall, great game. Keep making more!