# How can I identify prime numbers easily?

##### 1 Answer

Apr 8, 2016

There is no easy way with large numbers.

- List item

#### Explanation:

But you can exclude a lot of numbers by using the divisability rules:

- if it's even it's not a prime (only 2 is a prime)

- if the digits add up to a multiple of three, it's not a prime

- if it ends in 5 it's not a prime

And so on.