Primer

Press the red button to see the next prime number.

Will the next gap be long or short? Were you right?

What is the average gap between primes?

Prime numbers are whole numbers, greater than 1, than cannot be made by multiplying smaller whole numbers together. The gaps between prime numbers are unpredictable making them very difficult to find. This becomes very useful when sending secret information on the internet. In RSA, a key is made by multiplying two very large prime numbers together. This key is published and is public information for anyone who wants to send the code maker a secret. Only someone with the two original primes can decode the message. It is possible to work out the two primes from the public key, but when the primes are large this becomes so difficult that even modern computers can’t do it. So, any messages sent with the public key will remain safe. This is how your computer sends your secret information when buying things online.