SpeedBoo helps you to train your ability of mental arithmetic with an emphasis on multiplication. 93 x 97 will soon be an assignment for which you have the correct solution in just a few seconds. That is, because the app provides you next to an endless number of assignments also with some very clever tricks to handle them without a calculator in a reasonable time.
The app leads you from simple calculations step by step to higher level tasks. And its up to you how fast you want to go ahead.
So, have fun and impress you friends and colleagues with mental arithmetic soon.