mantissa
The mantissa stands for a mathematical notation of exponential values. In exponential notation, the mantissa is the factor that precedes the power of ten of another base. It, the mantissa, indicates the valence.
A complete exponential notation consists of the mantissa for the valence, the base of the power, and the exponent. The mantissa of 24.87 x 10exp12 is 24.87, the base is the number 10, and the exponent is 12. If the number 0.0034 is written exponentially, then you get 3.4 x 10exp-3. The mantissa is 3.4, the base is 10, and the exponent is -3.