Helps keep minds active with simple but challenging math drills that test your math skills. Choose the number of math drill questions in increments of 25, 50 or 100. Scores are based upon speed and accuracy level, which provide a brain's fitness level. Great for anyone who wants to brush up on simple math skills or exercise their brain. Also provides standard calculator functions and a right shift key for easy corrections. Power Source(s): Battery; Solar; Display Notation: Alphanumeric; Number of Display Digits: 10; Display Characters x Display Lines: 10 x 1.