The logarithm of a number is the exponent factor, to which the base, another fixed number, must be raised to produce that number.
The logarithms of the very same number vary from each other, in case of different bases.
Common logarithms are the logarithms with base 10.
The logarithm of a number consists of 2 parts; the 1st part is called Characteristic, whereas the 2nd part is called Mantissa.
Mantissa is the 2nd part of the logarithm of a number, which is a positive proper fraction.
The logarithm of a number is calculated by finding out its characteristic and mantissa and adding them up.