It has four computational area, and you can perform another calculation in each area. If you click on each area, the area becomes active, the character will be black. The characters of non-active area will be white. Pressing the "→" button on the right side of each area, the calculation result of the area is input to the active area, Since it is also copied to the clipboard at the same time, you can use in other apps. If you press the first symbol of operation, you can divert the previous calculation results.