Prime Numbers

Prime numbers are simple to understand, just remember their definition. A prime number is a number that can be divided by itself and 1 only and a prime number is bigger than 1.
Examples of prime numbers are 2, 3, and 7. However, lets look at whether 18 is a prime number. 18 can be divided by itself and 1, however it also can be divided by 2, 3, 6 and 9. As a result, it is not a prime number.

Understanding the definition a bit better


The definition says that a prime number is a number that can only be divided by itself and 1 only, however technically it is possible to divide by any number. For example, we said that 3 is a prime number because it can only be divided by 3 and 1. However, we CAN divide 3 by 2, 4, 50, 100 and every other number, however we would get decimals (not whole numbers) as answers. So when it comes to defining a prime number, it is a number that can only be divided by itself and 1, and no other number where a whole number answer can be achieved.
In our previous example, 18 is not a prime number because it can be divided by 3, to get 6, as 18/3 = 6, and 6 is a whole number.

Try answering these:

  1. Is 17 a prime number?

  2. Is 49 a prime number?


Answers:

  1. Yes, 17 can only be divided by itself and 1.

  2. No, as 49 can be divided by itself, 1 AND 7.