怎么解这道题?谢谢!

If upper-case and lower-case letters are considered as different letters,how many six-letter computer passwords are possible
a) with no repeated letters?
b) with at least one capital letters?

Thanks in advance!

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回复:怎么解这道题?谢谢! -xum57- 给 xum57 发送悄悄话 (114 bytes) () 01/11/2009 postreply 14:46:49

回复:回复:怎么解这道题?谢谢! -月明人倚楼- 给 月明人倚楼 发送悄悄话 月明人倚楼 的博客首页 (54 bytes) () 01/12/2009 postreply 17:25:21

回复:怎么解这道题?谢谢! -月明人倚楼- 给 月明人倚楼 发送悄悄话 月明人倚楼 的博客首页 (287 bytes) () 01/12/2009 postreply 20:07:20

P(52,6)-P(26,6)= 14492368800正确,谢谢! -xum57- 给 xum57 发送悄悄话 (39 bytes) () 01/13/2009 postreply 12:03:41

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