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# A to Z of Excel Functions: The LOG10 Function

25 October 2021

Welcome back to our regular A to Z of Excel Functions blog. Today we look at the LOG10 function.

The LOG10 function

For a given base, a logarithm states the power that the base must be raised to for a given number, e.g.

10 = 10 = 101 ⇔ log1010 = 1

100 = 10 x 10 = 102 ⇔ log10100 = 2

1,000 = 10 x 10 x 10 = 103 ⇔ log101,000 = 3

1 = 100 ⇔ log101 = 0

0.1 =  = 10-1 ⇔ log100.1 = -1

0.01 =  x  = 10-2 ⇔ log100.01 = -2

Therefore,

y = ab ⇔ logay = b

= ab-c ⇔ logay = b – c

y = ab.ac ⇔ logay = b + c

y = cn ⇔ logacn = nlogac.

The LOG10 function is not the ninth sequel of the LOG function, but rather it returns the base 10 logarithm of a number you specify.  Its syntax is given by

LOG10(number)

The LOG10 function has the following argument:

• number: this is required and represents the positive real number for which you wish to determine the base 10 logarithm.

Please see my example below:

We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every business day.

A full page of the function articles can be found here.

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