## Ulam Spiral

The Ulam spiral is a graphical depiction of prime numbers first popularised by mathematician Stanislaw Ulam in 1963. A Ulam spiral is created by creating a spiral of numbers and then highlighting the prime numbers.

Here is a spiral of all numbers from 1 to 99. Follow the increasing numbers from the red centre as it spirals outward to 99.

Here is the same spiral with only the prime numbers displayed.

## Create Your Own Ulam Spiral

If you want to create your own Ulam spiral then click here .

Try a starting value of 41 and note the number of prime numbers appearing on the diagonal.

You can re-load the spiral page at anytime to try new values.