Do you know what a prime number is? And why it's useful? #math #cybersecurity #education

Added: 2026-05-07

[00:00:00]I'm a mathematician and I'm currently surrounded by some of the leading experts in cybersecurity. And I'm here today to ask them one very important question. Do you know what a prime number is? Yes. Yes. I absolutely do know what a prime number is. So, a prime number is a number that is only divisible by itself and by one.

[00:00:17]>> And that really matters because this is the [music] math that helps keep your private information safe online. If I gave a computer two prime numbers like two and seven, multiplying them together is easy. But, if I gave you the answer 91 and [music] asked you which two prime numbers made that number up, you'd now have to work backwards.

[00:00:34]>> [music] >> For 91, that is still a pretty easy number. But, modern cryptography uses the same idea with prime numbers that are hundreds of digits long. A computer can multiply primes together very quickly, but [music] being given a number and then decomposing it into its original prime numbers is much more difficult for computers [music] to do.

[00:00:53]And this is why prime numbers are so useful in cybersecurity. [music] They let you share a big number publicly so someone can use it to hide a message for you, but then the original primes, they stay [music] secret. And without those primes, it becomes incredibly hard to work backwards and unlock [music] that hidden message. But, don't just take it from me. Here is what the director of GCHQ had [music] to say.

[00:01:15]Prime numbers are a really crucial ingredient of being able to have strong crypt.

[00:01:19]>> And if you're interested in learning more about cybersecurity, then comment cyber on this post and I'll send you all the resources to get started.