➽ A logarithm is the power to which a number must be raised in order to get some other number. For example , the base ten logarithm of 100 is 2 because 10² is 100 : log 100 = 2
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➽ The term is coined from the two ancient Greek terms logos, meaning proportion, and arithmos, meaning number; compounding them to produce the word “logarithm.” Napier used this word as well as the designations “natural” and “artificial” for numbers and their logarithms .