Prime Numbers

What Is a Prime Number?

A prime number is a number that can be divided by only itself and 1.

For example,

  • 2 is a prime number. It can only be divided exactly by 1 and 2 itself.

  • 3 is a prime number. It can only be divided exactly by 1 and 3 itself.

  • 4 is not a prime number. It can be divided exactly by 1, 2 and 4.

Dictionary Definition

The Oxford English Dictionary defines a prime number as "a number that cannot be divided by any whole number (without a remainder) other than itself and one."

The Prime Numbers

The prime numbers are:

In a number square, the prime numbers are shaded below:

These are just the prime numbers under 100. There are infinitely many prime numbers, they go on forever.

See Also

What is a natural number? What is a factor? What is a composite number? What is the fundamental theorem of arithmetic?