Math Fundamentals18 sections · 814 units
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Why Factorial Counts Arrangements

(Multiplying choices)

You have n distinct items. To arrange them in a line:

1.1. Pick the first item: n choices

2.2. Pick the second: n-1 choices remain

3.3. Pick the third: n-2 choices

4.4. Continue until 1 choice is left

Multiply: n × (n-1) × (n-2) × ... × 1 = n!