LESSON: Combinations & Permutations

Combinations & Permutations

Combinations and Permutations can look very similar, but they are very different. It's important for us to understand how each of these calculations are different so we can know which calculation to apply to a given problem.

The main difference to be concerned with is:

Say, for example, you want to sign in to your email account. You need to put in your password. The order that you type in your password matters. MHA_PASSWORD is different than HAM_PASSWORD. You wouldn't be able to open your email if you typed your password in the wrong order! In this case we're talking about a permutation.

Say though, for example, you are making a fruit smoothie. You throw some strawberries, grapes, pineapple and bananas into the blender. The order that you put these fruits into the blender doesn't matter. It's the same smoothie no matter what order you put in the fruit. Here we are talking about a combination.

Permutation problems will generally use words like "order" or "arrange".

Combination problems will generally use words like "group", "choose" or "select".

Watch the following video to see examples of how to determine if a problem requires a permutation or combination: