Maths question

Actually it's the factorial question.

The number of possible combination is 5!

5!
= 5×4×3×2×1
= 120

More specifically,
first A has 5 possible seats, then A chooses.
then B has 4 possible seats, then B chooses.
then C has 3 possible seats, then C chooses.
then D has 2 possible seats, then D chooses.
then E has only 1 possible seat, then E chooses.

So the number is 5×4×3×2×1 = 5! = 120.

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這是個 factorial 的問題。

總共有的可能性是 5!

5!
= 5×4×3×2×1
= 120

首先 A 選，他有 5 個可能的位子。
跟著 B 選，他有 4 個可能的位子。
跟著 C 選，他有 3 個可能的位子。
跟著 D 選，他有 2 個可能的位子。
跟著 E 選，他只有 1 個可能的位子。

所以總數是 5×4×3×2×1 = 5! = 120.

2006-11-27 21:41:08 補充：
小小補充：涉及到 all combination 的題目，多數是利用 factorial 來解決。