這條GRE的題，誰懂得做?

Sandy has a husband and 2 children. She brings at
least 1 member of her family to a diner for lunch
every day. The diner offers 10 lunch specials. If no
one orders the same thing, how many different orders
can Sandy’s family make for lunch?
Indicate all possible values.

答案選項分別是45，90，120，210，720, 5040

所有跟帖： 

• 似乎是簡單的排列組合問題，但我的算法怎麽都對不上啊。可能取決與定義 -abookl- ♀ (386 bytes) () 11/15/2014 postreply 13:37:42

• 你做對了 -bearsback- ♂ (104 bytes) () 11/15/2014 postreply 16:02:25

• Three possible answers: 45/120/210. -ZoyaWashington- ♀ (0 bytes) () 11/17/2014 postreply 21:29:30