The app generates random numbers whose range can be set.Depending on the type of calculation set, the tasks are then displayed after the user has started the calculation tasks.It must be released within the set time (1 to 60 seconds) by tapping the correct button. If the number of runs is set to 1, the result is evaluated immediately after tapping. Red result means wrong answer, green correct answer. If multiple runs are set, the results are displayed on the "Results" page, incorrect red - correct green. The 3 pages of the app can be displayed by swiping to the right or left or by tapping the lower 3 buttons "Calculations", "Results" and "Description".