`Sqrt()`

Examples¶

Returns the square root of a given positive `double`

.

Returns `NaN`

value if used with negative number.
`NaN`

is a field in the `Double`

class.

`NaN`

stands for “Not a Number” and in this case,
the square root of a negative number does not exist.
It is imaginary, or not a number.

You can read more about `NaN`

in the Microsoft documentation.
And the square root method here.

**General Syntax**

```
Math.Sqrt(doubleNumber);
```

Example

1 2 | ```
Console.WriteLine(Math.Sqrt(9));
Console.WriteLine(Math.Sqrt(-9));
``` |

**Console Output**

```
3
NaN
```