characteristic

In mathematics, the integral (whole-number) part of a logarithm. The fractional part is the mantissa.

For example, in base ten, 100 = 1, 101 = 10, 102 = 100, and so on; the powers to which 10 is raised are the characteristics. To determine the power to which 10 must be raised to obtain a number between 10 and 100, say 20 (2 × 10, or log 2 + log 10), the logarithm for 2 is found (0.3010), and the characteristic 1 (log 10) added to make 1.3010.