# Definition:Approximation

## Definition

An approximation is an estimate of a quantity.

It is usually the case that there exists some knowledge about the accuracy of the estimate.

The notation:

$a \approx b$

indicates that $b$ is an approximation to $a$.

## Examples

### $\dfrac {22} 7$ as an Approximation for Pi

$\dfrac {22} 7$ is a convenient approximation to $\pi$:

$\dfrac {22} 7 = 3 \cdotp \dot 14285 \dot 7$

## Also see

• Results about approximations can be found here.