Not correct school - puzzle game

Not correct school is a free online flash game of the category puzzle games.

Very a complex mathematical game.
Necessary to correct the critical error.
Try manage without the help .
Try solve the math problem quickly and correctly

mouse left key - delete, mouse left - add.

A context menu should be shown when right-clicking or, on touch devices, long-pressing in the game. This menu especially allows to play in full screen and control the volume.