1234123121 究竟可以砌出幾多個不同的數字呢?

因為有4個1, 3個2, 2 個3, 1個4
用組合數學公式
不同的10位數字
=10!/(4!*3!*2!*1!)
=12600個


2007-01-02 00:45:35 補充：
我找番關於條公式既資料啦﹐參考http://hk.knowledge.yahoo.com/question/?qid=7006122900266

the number of ways of arranging n objests in a line which p of one type being alike,q of another type being alike,and so on are n ! ÷(p !)(q !)...
for 1234123121
i.e arangement =10 ! ÷(4!)(3!)(2!)=12600
since, there are 10 numbers,the n.o "1'' exists fourth times,2 exists third times,3 exists twice and 4 exists once only.
let 's see some example(s) to have clearly understand~

how about n.o of ways arranging ''abcd''??
the answer is 4!

so in how many ways can the letters of words ''apple''be arranged?
ans.=5!÷2!=60
我d英文未達必太好~~見諒

10! / 4! X 3! X 2!

=12600