  
[https://app.mentalarithmetic.no/](https://app.mentalarithmetic.no/)

  
**Turn-based two-player crossnumber math game: Build valid equations with numbers and math signs.**

Mentamic is a turn-based online math and number game where you build valid equations on a 9×9 board using numbers, operators, equals signs, and parentheses.

What sets Mentamic apart from many other math apps is that you do not just compete against yourself. You can challenge friends, invite new players with a link, face random opponents, and improve your rating.

In the app, you can:

* Play 2-player games or practice in solo game or play against bot.
* Invite friends via SMS or email etc.
* Find and add other players if you know their username.
* Chat with your opponent during the game.
* Choose thinking time per move from 10 minutes to 3 days
* Track ELO rating and solo highscores
* Use +, -, ×, ÷, powers, nth roots and parentheses.
* Continue ongoing games later

Every move is about strategy, mental arithmetic, and pattern recognition on a complex board. Build expressions that intersect, use parentheses wisely, and maximize your score on the board.

Mentamic is for anyone who enjoys brain training, number games, logic games, and competition. Whether you want to practice on your own or play against others, you get a math game with depth, social interaction, and a competitive edge.

I created Mentamic - a two-player math game for iOS and Android