问道题：6个学生分成3组，有几种分法？

xjlv128

大家当作魔板记吧，说 均分 的时候，通常除以组数的全排列

mejor

同意楼上的，均分书，均分人，均分球，均分汽车，都是这样的，先按正常的做，然后，除以相同组的全排列，就好了，比较容易错。

iris555999

以下是引用lovetiky在2006-7-9 14:24:00的发言：

C(6,2) means in step 1, choose 2 randomly from 6, and mark "this is group 1"

C(4,2) means in step 2, choose 2 randomly from 4, and mark "this is group 2"

C(2,2)=1 means in step 3, choose 2 from 2, and mark "this is group 3"

now, we have group 1, group 2 and group 3, but they are permutations because they include the order.

but in this question, we do not have to consider the order, so there is a division.

Thank you so much!