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# atan

```the atan of number ``` Value returned: number equal to the trigonometric arc tangent of` number `expressed in radians

Note: There are 2 * pi radians in 360 degrees.

## Placeholders

number
An expression that evaluates to a number.

For example:

```169 / 19 pi (60.625 * 500) average(1,4,5,10) i+1 -- (where i is a number) line 1 of fld "Debits"```

Note: Formally, HyperCard distinguishes between factors (simple values) and expressions. The difference between factors and expression matters only if you like to drop parentheses. Most functions take factors as their parameters, which is why` abs of -10 + 2 `returns` 12 `and `abs of (-10 + 2) `returns` 8`. In short, always use parentheses to group things the way you want them to evaluate, and you wonâ€™t have to worry about the difference between factors and expressions.

## Related Topics

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