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### Course: Pixar in a Box>Unit 5

Lesson 2: Counting crowds

# 5. Does order matter?

Why do we divide the number of combinations by the number of permutations? If we have 4 actors (A, B, C, D) and we need to pick 3, we can arrange them in different ways. But, we don't want to count the same group twice just because they're standing in a different order. So, we divide by the number of ways the 3 actors can arrange themselves.

## Want to join the conversation?

• Am I the only one who doesn't get the "bingo! that's it!" moment she gets at min . I don't see at all the relationship between what she explained about permutations some seconds before and the seemingly arbitrary formula she's presenting afterwards.
• Me: Doesn't do the practice and saves it for tomorrow because i'm lazy
Her: gOoD wOrK
Me: i- i didn't even do anything-