Basic arithmetic operations with AddUp are performed by entering
numbers and operators to form the expression to evaluate. The expression
can be typed in and edited at will, then pressing the `Enter`
key causes it to be evaluated. There is no need to use buttons with this
calculator, everything that needs to be evaluated can be directly entered
in the work area.

The basic arithmetic operators are:

- Addition: +
- Subtraction: -
- Multiplication: *
- Division: /

Other frequently-used operators are:

- Percent: % (for example, 5% = 0.05)
- Factorial: ! (for example, 5! = 120)
- Power (exponent): either ^ or ** (for example, 3^2 = 9)

Parentheses can also be used to nest sub-expressions. For example:

`1 + (2 * 3) = 1 + 6 = 7`

`(1 + 2) * 3 = 3 * 3 = 9`