T, W, P (Solar and Auxiliary Batteries): Unlike traditional solar powered calculators, the built-in battery protects the calculation contents even if the light is interrupted during calculation.Multi% Quarter-Constant Calculation Approx. Calculation Digit Reduction (Shift): For correcting inputs errors.Erase minimum digits per digit+/-(Sine Change): Use to switch positive number (+) to negative number (-) and vice versa.Quick Press Function: When you enter the next key, you can start pressing the previous key from the middle of the talk of the previous key.3 digit scale display oversized plastic key auto power off