Henry Briggs (mathematician) in the context of "Fractional part"

The fractional part or decimal part of a non‐negative real number ${\displaystyle x}$ is the excess beyond that number's integer part. The latter is defined as the largest integer not greater than x, called floor of x or ${\displaystyle \lfloor x\rfloor }$. Then, the fractional part can be formulated as a difference:

The fractional part of logarithms, specifically, is also known as the mantissa; by contrast with the mantissa, the integral part of a logarithm is called its characteristic. The word mantissa was introduced by Henry Briggs.