LESSON: Combinations

Intro to Combinations

In the previous lesson we looked at situations where the order of an arrangement is important. For example, when looking at 3-digit numbers, the number 123 is very different from the number 312, even though it contains the same 3 digits. 

But in some situations, the order is not important – for example, when looking at cards in a hand of poker, or choosing toppings to put on a pizza. In these situations, when order is not important, we are looking at combinations of items. 

For example, if you are a poker player you might want to know the probability of being dealt four aces in a hand of five cards. You don’t care in which order you receive the ace cards – only the fact that you have four of them is important.

Similarly, if you are ordering a pizza, you don't care about the order that they put the toppings on your pizza. You only care if all the toppings are on top of the pizza!

In these examples we can see that ORDER DOESN'T MATTER!