# Definition:Wallis's Number/Historical Note

## Historical Note on Wallis's Number

The cubic $x^3 - 2 x - 5 = 0$ was used by John Wallis as a example to demonstrate how Newton's Method could be used to solve certain equations numerically.

The real root of this equation has since become known as Wallis's number.

It has subsequently been used as a test for a number of different methods of approximation.

It is known to over $4000$ digits.