# Futurebasic/Language/Reference/annuity

## FN Annuity#

### Function

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### Syntax

annuityFactor# = fn annuity#( rate, periods )


### Description

Returns the annuity factor for the given interest rate and number of periods. The interest rate should be expressed as a fraction of 1; for example, 5.2 percent should be expressed as 0.052.

### Notes

fn annuity# uses the following formula:

${\displaystyle annuityFactor\#={\frac {1-(1+rate)^{periods}}{rate}}}$

compound