Mantisse

Mantisse is a term used in various fields, most notably in mathematics and computing, to refer to the fractional part of a number. In the context of logarithms, the mantissa is the part of the logarithm that remains after the integer part, known as the characteristic, has been removed. For example, the logarithm of 123 is approximately 2.0899. Here, 2 is the characteristic and 0.0899 is the mantissa. The mantissa determines the sequence of digits in a number, while the characteristic determines its magnitude or order of magnitude.

In floating-point representation, which is how computers store numbers with decimal points, a number is typically expressed as a product of a significand (or mantissa) and a power of a base. This significand is the fractional part of the number, usually normalized to be between 1 and the base (exclusive of the base). For instance, the number 123.45 might be represented as 1.2345 × 10^2. In this representation, 1.2345 would be considered the significand or mantissa, and 2 is the exponent. The term "mantissa" in this computing context can sometimes be used interchangeably with "significand," though technically a significand can include an integer part before the decimal point, whereas a mantissa is strictly the fractional part. This distinction is important in understanding how numbers are stored and manipulated in computational systems.