[計量] 一題排列組合
請問
下面這題我不太清楚題意
懇請高手解惑
During a dance class, each of the twelve students is paired up
with eash of the other students twice.
How many total pairings will there be during the class?
答案是132
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推
08/18 21:59, , 1F
08/18 21:59, 1F
推
08/18 22:00, , 2F
08/18 22:00, 2F
→
08/18 22:00, , 3F
08/18 22:00, 3F
→
08/18 22:02, , 4F
08/18 22:02, 4F
→
08/18 22:05, , 5F
08/18 22:05, 5F
→
08/18 22:06, , 6F
08/18 22:06, 6F
→
08/18 22:09, , 7F
08/18 22:09, 7F