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Excel LOG Function

Excel LOG function
Summary 

The Excel LOG function returns the logarithm of a given number, using a supplied base. The base argument defaults to 10 if not supplied.

Purpose 
Get the logarithm of a number
Return value 
The logarithm
Syntax 
=LOG (number, [base])
Arguments 
  • number - Number for which you want the logarithm.
  • base - [optional] Base of the logarithm. Defaults to 10.
Version 
Usage notes 

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.

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