I recommend the number sense planet app. This app was used by my girl from mathematics enlightenment to the third day of this year. It is really helpful for children to learn math. It is said that this software uses Singapore mathematics teaching method, Baidu answers you.

This exercise is synchronized with the school textbook and made into a game form, which is very interesting, and a point will toss out many kinds of questions, teaching children to learn to draw inferences while consolidating. I feel that my girl's brain is very lively now, and I don't know if she is practicing the problems on the digital planet. Ha ha.