Web tool for math learning

I made some tools online in recent years and love to see they are useful, helpful.

One of them is to make arithmetic exercise quizzes. Working out the exercise is one of the learning method of Chinese kids. Some data of schools proved that the mathematical foundation of Chinese teenagers is better than those from America and Europe.

The UI of the web application is in Chinese, it could be translated into other languages, or be transformed to desktop application or mobile App, if anyone requires.

here is the link of the web application: http://zuokantan.cn/tool/Suanshu/