If you are unable to see numbers on the maths keyboard, this is usually linked to the size of the screen on your device. Please try moving your device into landscape mode to view more of the keyboard.
If you are still unable to see the numbers, you can scroll along the keyboard by moving your finger from right to left across the screen. This will scroll to the numbers which are on the far right hand side of the keyboard.
Please note that CENTURY is not optimised for use on mobile phones.