- A numeric format in which each number is represented by two numbers, and in which the decimal point is not in a fixed location. The first number, the mantissa, specifies the significant digits, while the second number, or exponent, specifies its magnitude. For example, 314,000,000 may be expressed as 3.14 × 108. Although any number, with any radix, may be represented in this manner, it is usually used only for very small or very large numbers. Also called floating-point notation, or exponential notation. When an E is used instead of a 10, or the radix utilized, it is also called E notation.