Fun Calculator FREE - Keep your brain young

The feature of my app is a calculator that provides 4 operations: add, subtract, multiply and divide. It also has the converter of 10 bases to binary, hex, and oct. Besides the calculator itself, I also build a game mode for practicing mental arithmetic. During the limited time, the APP asks user random mathematical questions. The user has to answer the question as fast as possible in order to gain more points during the given time. The goal is to gain points as many as possible. I hope while people are using my calculator they can also sharpen their skill of mental arithmetic. * If you think this APP is helpful, you can send me donation via paypal. Any amount of donation will help and be very much appreciated! you will find my email in the additional information.