A mantissa and exponent are used in floating point representation to store real (decimal) numbers in binary. The mantissa holds the significant digits of the number, determining its precision, while the exponent controls the position of the binary point, determining the range of values that can be represented. Together, they allow computers to efficiently store both very large and very small numbers.

Changing the number of bits allocated to the mantissa or exponent affects how a floating point number is represented, specifically impacting its precision and range.