# Thread: what are prime numbers?

1. ## what are prime numbers?

a prime number is a number that can be divided only by itself and 1. i get that. i also google searched it and another thing i read about it is that these numbers are the building blocks of mathematics.
what does that even mean? what is the significance of a prime number? what's it's function, it's application. what do we need them for. what do they represent?what's their importance?

2. ## Re: what are prime numbers?

Originally Posted by mohsentux
a prime number is a number that can be divided only by itself and 1. i get that. i also google searched it and another thing i read about it is that these numbers are the building blocks of mathematics.
what does that even mean? what is the significance of a prime number? what's it's function, it's application. what do we need them for. what do they represent?what's their importance?
a prime number is a number that can be divided only by itself and 1.
If one uses that definition then 1 is a prime number. We don't allow that.

A positive integer is prime if and only if it has exactly two divisors. Do you see how that excludes 1 from being prime?
Hint: 1 has only one divisor. One of the fundamental theorems states that any positive integer is the product of powers of primes.
For example: look at this.
You can see the prime factors of 90508000.

3. ## Re: what are prime numbers?

Originally Posted by mohsentux
a prime number is a number that can be divided only by itself and 1. i get that. i also google searched it and another thing i read about it is that these numbers are the building blocks of mathematics.
what does that even mean? what is the significance of a prime number? what's it's function, it's application. what do we need them for. what do they represent?what's their importance?
Primes are useful in many different branches of mathematics. Your question is too broad to be answered effectively, especially in a pre-university forum. The most concrete example I can give you is cryptography. This is one of MANY applications of prime numbers, but an important one. Here is a wikipedia entry for RSA encryption.

https://simple.wikipedia.org/wiki/RSA_algorithm

4. ## Re: what are prime numbers?

actually that helped out a lot. i'm currently studying c syntax and programming. when i'm at an acceptable level in programming i'll be joining a group that specializes on lossless/lossy compression, encoding/decoding of images/video, cryptography(AES) etc...
now that i know prime number play key role in such area I'll spend more time on understanding it.