 Numerals

On a Casio calculator you can enter the numerals 0 - 9 with the keys

 0 1 2 3 4 5 6 7 8 9

Example 1

To calculate 0 × 1 = 0  0 × 1 = 0×1            0.

and also 0 × 0 = 0  0 × 0 = 0×0            0.

Example 2

To calculate 0 ÷ 1 = 0  0 ÷ 1 = 0÷1            0.

Example 3

Enter 1 ÷ 0  1 ÷ 0 = Math ERROR

and also 0 ÷ 0  0 ÷ 0 = Math ERROR

Dividing by zero always gives a message, and that is correct.

Example 4

To calculate 10 = 1   1 ∧ 0 = 1∧0            1.

Example 5

Enter 00   0 ∧ 0 = Math ERROR

although it is determined per definition that 00 ≝ 1. Take that as a warning.

Example 6

Enter 0!    0 x-1 = 0!            1.

This is correct, then it is determined by definition that 0! ≝ 1.

Example 7

To calculate cos (0) = 1    cos 0 = cos 0            1.

Example 8

To calculate √0 = 0  √ 0 = √0            0.

Example 9   0 nCr 0 = 0C0            1.

Details

In the decimal system you need the 0 to indicate that a place in a decimal number has no value, as in the number 12305. The total value of a number can also be 0.