A number wall (also number triangle, number pyramid or number tower) is a didactic means for learning the basics of addition. An ordinary number wall is pyramid-shaped and each cell is equal to the sum of the two below it.
The number wall is an operational form of exercise with which differentiated levels of difficulty can be realized. It is often used in 1st to 4th grade. Depending on how the values are entered in the cells, the person solving the number wall has to use different operations. If the basic series is completely filled, only addition is applied, if the values spread out, knowledge of subtraction is also needed. These basic mathematical skills and competencies are thus practiced.