A long time ago, I read a perfect book. I really like that kind of stuff. The main problem I had back then was trying to train my skills. It is so much fun to use this method to solve math problems, but it is absolutely not as fun to create those tasks for yourself. I thought a lot about how to do it and tried several apps, but they didn't offer what I wanted. I wanted pure math—no gamification, no ads, just examples to solve.

Moreover, I really like multiplication by 5 (even numbers). It is so simple and so impressive when you show someone how you can multiply any number like

in seconds. I am glad I met people who are interested in it as well. The story of Trachtenberg is unique, and that's a fact.

I decided to make a small app for training, and I found that the most interesting part is multiplication. Maybe I will add some other operations in the future. If you want, you can try it out. It is free, requires no registration, has no annoying ads, and so on—just pure math. I hope you like it!

https://play.google.com/store/apps/details?id=com.milvus.grema