You can perform simple aritmetic operations on the Linux shell command line, without using any external program.

use the command `expr`

These are the aritmetic operations.

- Add
- Substract
- Multiply
- Divide
- Reminder of a divition

expr 1 + 2

expr 2 - 1

expr 2 \* 1

expr 2 / 1

expr 20 % 3

Note that for multiplication we escape the * character, with the back slash, and that the % operand gives as the reminder of a divition, also the divition is only giving as the Integer