App is useful when calculating the many numbers.
Usually, when you do the calculations each time, you must press math symbols, and then press the numbers, but there is not a like that necessity.
You only need to set the operation symbols and digits, simply press the numbers
For example, If you add operation(1 to 9), You need to press the numbers and + alternately. But, there is not a like that necessity. Once, you set the + and dits. You simply press the number.
Also, it is provided calculation history to users.
Calculation history is reviewing tool.
But, the free ver. doesnt support edit mode.