- The decimal part of a logarithm. The integer portion is the characteristic (3). For example, if a logarithm of a given number equals 1.2345, the mantissa is .2345, while 1 is the characteristic.
- In a floating-point number, the first part, which specifies the significant digits, and which usually has a value equal to or greater than 1, but less than 10. For example, in 1.234 × 1056, 1.234. The power to which the base is raised, 56, is the characteristic (2).