How to use the LOG10 function
What is the LOG10 function?
The LOG10 function calculates the logarithm of a number using the base 10.
Table of Contents
1. Introduction
What is a logarithm?
In logarithms, the base is the number that is raised to a power to produce the desired output. It is the foundation of the logarithmic function.
What is the log10?
The logarithm base 10, or log10, also known as the common logarithm, is the special case where the base is 10:
log10(x) = y where x and y are numbers such that 10^y = x
In other words, log10(x) is the power that 10 must be raised to in order to equal x.
What is the definition of a logarithm with an base of 10?
For the base 10:
log10(x) = lim (n->infinity) (x^(1/n) - 1) * n / log10(e)
Where:
-
- 10 is the base
- x is the input number
- e is the mathematical constant (approximately 2.71828...)
This limit definition comes from Euler's Logarithm Definition, relating logs of any base b to the natural log ln(x).
What is a base?
In logarithms, the base is the number that is raised to a power to produce the desired output. It is the foundation of the logarithmic function.
For example, the logarithm log10(100):
- 10 is the base
- 100 is the input number
- 2 is the exponent that makes 10 return 100 because 102Â = 100
The most common bases are
- 10
- e (natural log), and
- 2 (for computers).
But any positive number besides 1 can be a base.
What are the four key logarithm rules?
The following rules are essential to learn if you want to solve various equations involving natural logarithms effectively.
- Product rule
log10(x*y) = log10(x) + log10(y)
The log10 of the multiplication of x and y is the sum of the log10 x and log10 y.
Example, log10(5*10) = log10(5) + log10(10) - Quotient rule
log10(x/y) = log10(x) - log10(y)
The log10 of the division of x and y is the difference of the log10 x and log10 y.
Example, log10(5/10) = log10(5) - log10(10) - Reciprocal rule
log10(1/x) = − log10(x)
The natural log of the reciprocal of x is similar to the quotient rule. log10(1/x) = log10(1) - log10(x) = 0 - log10 x = - log10 x
Example, log10(1/5) = - log10(5) - Power rule
log10(xy) = y * log10(x)
The log10 of x raised to the power of y is y multiplied by the log10 x.
Example, log10(510) = 10 * log10(5)
What are the other logarithmic functions in Excel?
Excel function | Description |
---|---|
LOG | Returns the logarithm with a given base. |
LN | Returns the natural logarithm (base e) of a number |
LOG10 | Returns the base-10 logarithm of a number |
LOG2 | Returns the base-2 logarithm of a number |
The corresponding inverse functions for the logarithm functions in Excel:
Logarithm | Power to |
---|---|
LOG | Arbitrary base, basex or POWER(number, power) |
LN | EXP(number) |
LOG10 | 10x or POWER(10,x) |
LOG2 | 2x or POWER(2,x) |
2. LOG10 Function Syntax
LOG10(number)
3. LOG10 Arguments
number | Required. A value larger than 0 (zero) that you want to calculate the logarithm with base 10. |
4. LOG10 Function Example
Formula in cell C3:
5. LOG10 not working
The LOG10 function returns #NUM! error if number is equal to 0 (zero) or smaller.
6. How to raise a number to the power of
The POWER function lets you raise a number to the power of a specific value. For example, =POWER(10,2) is the same as 102 equals 100.
The caret character lets you also raise a number to the power of a specific value, it is smaller than the POWER function which then makes your formulas smaller. For example, =10^2 is the same as =POWER(10,2) or 102 which equals 100.
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Functions in 'Math and trigonometry' category
The LOG10 function function is one of 73 functions in the 'Math and trigonometry' category.
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