# Mantissa

The mantissa is the fractional part of a common logarithm (that is, the base 10 logarithm), which represent the digits of the given number but not its order of magnitude.

For example, the mantissa of both $\log_{10} 20 \approx 1.3010$ and $\log_{10} 200 \approx 2.3010$ is $0.3010$.

Note that the mantissa of $\log_{10} 0.2 \approx -0.6990$ is also $0.3010$. This is because the fractional part must always lie between $0$ and $1$. In this case, $-0.6990=-1+0.3010$, so the integer part is $-1$ while the fractional part is $0.3010$.