Red-Zero: math, addition and subtraction

Mathematical, free, educational and easy game that consists of getting zero at the end of each row and column through calculation with addition and subtraction. RED-ZERO is a mathematical logic game of addition and subtraction that speeds up the mental calculation in both children and adults. It takes patience, visual acuity, and logical thinking ability. RED-ZERO is played in a 5x5 network, subdivided into rows and columns. The game starts with some boxes already filled with numbers. The objective is to fill in the empty boxes so that, with additions and subtractions of each row from left to right, and from each column from top to bottom, get the result to be zero. For this only numbers from 1 to 9 will be used.