So far, I have only used while loops to determine if a number is prime or not. For today, I am going to explain to you how you can use ** for loop **to tell if a number is prime or not.

To understand the code below, you first need to…

In my last blog, I showed you the slower version of how to tell if a number is prime or not. Last time, I promised you that I’d show you the faster version in my next blog.

*So, here it is:*

`x = 17`

i = 0

length = len(the_primes)

the_primes = [2,3,5,7,11,13]

is_prime = True

while i < length:

if x % the_primes[i] == 0:

is_prime = False

break

i = i + 1

if is_prime == True:

print((f'{x} is a prime number!'))

else:

print((f'{x} is not a prime number'))

** Input:** x = 17

** Output:** 17 is a prime number!

I found out that you really don’t have to divide it by all the numbers before the number. You only have to divide it by *the prime numbers*** before** it.

A prime number is a number greater than 1 that is not a product of two smaller natural numbers. For example, 3 is prime because the only ways of writing it as a product, 1 × 3 or 3 × 1, involve 3 itself. But 6 isn’t a prime number…