# Exponential

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1. *Financial maths - constant.*

The exponential *constant* is a mathematical constant with a value of roughly 2.718282..., usually denoted by the letter *e*.

2. *Financial maths - function.*

The related exponential *function* is *e*^{x} (*e* to the power of x). The exponential function in Excel is =EXP( ). The exponential function is the inverse of the natural logarithm.

3. *Growth.*

Exponential *growth* means growth other than straight-line.

For example, the series 100, 200, 400... is growing exponentially.

4. *Decay.*

Exponential *decay* means the reduction in a variable, for example over time, on a basis other than straight-line.

For example, the reduction in the time value of an option, as its remaining time to maturity expires.