00:01
How many positive integers less than are equal to 36 are relative prime to 36, including the number one? well, if we just list our prime numbers, 36 isn't that big of a number that we can easily figure this out.
00:15
So prime numbers, and we want to include one.
00:21
Two is a prime number.
00:23
It's easy to confuse two is not being a prime number because we think of all even numbers being divisible by two.
00:29
But if i look at the factors of two, it's just two and one.
00:33
And the definition of a prime number is anything where its factors are itself, which the two is, and one.
00:40
So two is in fact a prime number.
00:43
So don't forget about two.
00:45
So one, two, three is a prime number.
00:48
Four is not.
00:49
We get five...