能说一下，15，20，15 是怎么回事吗？

所有跟帖： 

• 15 is # of combination of 4 numbers out of 6, 20 is 3 out of 6. -Kamioka- ♀ (0 bytes) () 04/12/2012 postreply 09:25:49

• 谢谢。有点懂了。 -琼岛春荫- ♀ (0 bytes) () 04/12/2012 postreply 09:32:00

• 回复：15 is # of combination of 4 numbers out of 6, 20 is 3 out of -Kamioka- ♀ (1633 bytes) () 04/12/2012 postreply 09:37:45

• 回复：回复：15 is # of combination of 4 numbers out of 6, 20 is 3 out -泥佛- ♀ (483 bytes) () 04/12/2012 postreply 10:35:28

• I answered Q2 upstairs, please grade. :) -Kamioka- ♀ (281 bytes) () 04/12/2012 postreply 10:52:55

• and thanks for correcting the 20. -Kamioka- ♀ (0 bytes) () 04/12/2012 postreply 11:03:51