## Purpose

## Return value

## Syntax

`=LOG(number,[base])`

*number*- Number for which you want the logarithm.*base*- [optional] Base of the logarithm. Defaults to 10.

## How to use

The LOG function returns the logarithm of a given number, using the provided base.

The LOG function takes two arguments, *number* and *base*. The value provided for *number* should be a positive real number. The *base* argument represents the base of the logarithm. *Base* is optional and defaults to 10 if not provided.

### Examples

The logarithm of 16 with base 2 (the power to which 2 must be raised to equal 16) is 4:

```
=LOG(16, 2) // returns 4
```

The logarithm of 100 with base 10 (the power to which 10 must be raised to equal 100) is 2:

```
=LOG(100,10) // returns 2
```

Because the base argument defaults to 10, the formulas below are equivalent:

```
=LOG(100,10) // returns 2
=LOG(100) // returns 2
```

The LOG10 function also returns the base 10 logarithm of a number:

```
=LOG10(100) // returns 2
=LOG10(1000) // returns 3
```

### Notes

- If
*number*or*base*are not numeric, LOG returns #VALUE! - The LOG10 function also returns the base 10 logarithm of a number.