Primary Mathematics/Prime numbers

Prime numbers are positive numbers greater than one that cannot be divided evenly by any positive whole numbers other than one and themselves. For example, 7 is a prime number because the only numbers that divide it evenly are 1 and 7, but 8 is not a prime number because, in addition to 1 and 8, the numbers 2 and 4 also divide it. An equivalent definition is that a prime number is a number greater than one that cannot be written as the product of two smaller positive integers.

The first 10 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29.

Numbers greater than one that are not prime are called composite numbers. Note that the number 1 is neither prime nor composite, but is instead classified as a unit.