google it

http://wiki.answers.com/Q/What_is_the_missing_number_in_this_series_73_12_6_3_5_4_4

Seventy three has 12 letters

twelve has 6 letters

six has 3 letters

three has 5 letters

five has four letters

Four has four letters

Four has four letters

Four has four letters

所有跟帖： 

• 哈哈，后面就是没完没了的４ -DTMom- ♀ (0 bytes) () 09/12/2013 postreply 08:22:09

• 晕倒。不知道楼主这题是作业吗。那家长非得跟这老师急。 -monochrome- ♀ (0 bytes) () 09/12/2013 postreply 08:51:15

• 没事的，小孩自己都知道。我们是因为没在这儿上过小学，所以使劲往数学上想 -DTMom- ♀ (0 bytes) () 09/12/2013 postreply 08:56:41

• 但是这要是算数学作业，我觉得会混淆小孩的数学思维的。别当数学作业就好多了 -monochrome- ♀ (0 bytes) () 09/12/2013 postreply 08:58:55

• 以后看到标题上写着小学数学题之类的千万别上当。 -混日子了- ♂ (0 bytes) () 09/12/2013 postreply 09:01:02