Relatively prime

"Relatively prime" means that two numbers don't have any common factors other than 1. Just like how two friends who don't have any shared interests are relatively prime friends.

For example, let's take the numbers 8 and 15. Both 8 and 15 can be divided by 1, but besides that, they don't have any common factors. 8 can be divided evenly by 2 and 4, but 15 can't. On the other hand, 15 can be divided evenly by 3 and 5, but 8 can't. So, 8 and 15 are relatively prime to each other.

Why is this important? Well, when two numbers are relatively prime, it means that there isn't any way to simplify their fraction. For instance, if you have a pizza that is cut into 8 slices, and you want to share it equally with a friend who wants 15 slices. If the numbers aren't relatively prime, you may have to change the size of your slices to make it fair. But if the numbers are relatively prime, it means we can't find any factor to divide both numbers, so we can't make the slices equal.

Being relatively prime also helps in cryptography and number theory, and helps us understand the fundamental theorem of arithmetic, which states that any number can be expressed as a unique product of prime numbers.