Sum of every rows and column must match the specified number at the end of a row or a column. You may solve the puzzle with a set of algebraic equations or calculate it in your mind.
Fill in the blank cells with positive or negative numbers. The red cells will turn green as you provide the solution for a row or a column. Often, more than one solution is possible.
You may check the solution by pressing the "See a Solution" button or start a new game by pressing the "New Game" button.