This software is intended to elementary school children, who are learning calculation. Thanks to it they will be able to work and play with the mental calculation, especially the multiplication tables. It also demonstrates the techniques of the four operations and provides a very useful step by step mode. The following topics are available : •Configuration This activity allows selecting the kind of operations and the difficulty level that will be used in the mental calculation module. •Mental calculation This activity allows working the mental calculation in an original way based on falling operations that have to be put toward the right solution before they have reached the bottom. •Operations techniques This activity shows the different steps used to properly solve a complex calculation. A step by step mode helps the child to learn. This module also gives the chance to check a calculation done in a book.