Find the logarithm of a number to any base. Enter the number and the base, and the calculator shows the log, along with the natural log and the log base 10. A logarithm is the reverse of a power: it tells you the exponent the base needs to reach the number.
The calculator uses the change of base rule: the log of a number to a base is the natural log of the number divided by the natural log of the base. The number must be greater than zero, and the base must be positive and not equal to one.
Log base 10 of 1,000 is 3, because 10 cubed is 1,000. The natural log of 1,000 is about 6.908, and log base 2 of 1,000 is about 9.966.
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