"Brain Number" is a calculation game which you do a sum in your head as soon as possible.Enjoy calculation and know your brain power!There are three levels with a different difficulty.First of all, let’s test your power from an easy level, and let’s try to harder level after that!Or, do you challenge at the most difficult level at first?This game has international and domestic ranking. Complete all questions, and send the score of time that you take.Can you put your name on the leaderboard also?