The program gives hints when the given answer is wrong (send me your tips if you have some more). The preferences dialog (from the Menu button) allows adaptation to most levels of difficulty required by children in different ages:
* maximum of operands or result,
* integer or decimal (with up to four decimal places) operations,
* with or without carry over,
* multiplication and addition tables training,
* number of authorized tries,
* and some few others...
There is a timer but it is shut-off by default, as to not stress sensible children. Finally, the language of the app can be set different (English, French, German) from the default.
The challenge mode (reachable from the menu in the first dialog) allows children to play against themselves and others with predefined challenges and a high-scores list.
This app is Open Source under Gnu Public License version 3 or later (GPLv3+).