Primes

Writers normally name their stories in sequence - Chapter 1, Chapter 2, Chapter 3, ....

This story book I'm reading, the writer named his chapters 2, 3, 5, 7, 11, 13,17, 19, and so on. The last chapter is 233.

Do you recognize these numbers? Yes, they are prime numbers or primes.

Remember what primes are? Well, they are numbers which have 2, and only two, factors and the factors are itself and 1.

So, 4 is not a prime number because it has 3 factors - 1, 2, 4. Also, 1 is not a prime number because it has only 1 factor - 1.

Mathematicians are intrigued by prime numbers because prime numbers have no formula and there are also no patterns. There is no formula to tell you if a very big number, say 21203, is a prime number or not. There is also no formula to find out for example what is the 1000th prime number.

Mathematicians may know the largest prime number to date but there is always the next one waiting to be discovered.

All these may be useless information for us. But I read that prime numbers have some very important applications. They have to do with secret codes.

The fact that the writer used prime numbers to name his chapters tells us that he loves mathematics.