The number on the screen may be removed and restored.
The number on the display can be changed by just waving your hand or shaking the calculator.
The pattern of number may be customized.
The screen can be reset by just wiping though it using any fabric.
The magician can calculate the phone number or any specified number combination to the audience.
The product may be given to the audience for examination.
It has exactly the same behavior as a normal calculator when not performing.