Two n digit integers are said to be equivalent if one is a permutation
of the other. for eg. 10075 and 01057 are equivalent.
Find the number of 5 digit integers such that no two are equivalent
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3 Answers
62This question is same as number of 5 digit numbers a1a2a3a4a5 such that
a1>=a2>=a3>=a4>=a5
Now it should be easy?
62see teh hint says that if you arrange a1>a2>a3>a4>a5, then any other arrangement of these numbers will be equivalent.
So just by counting all such arrangements, we are done
for instance lets take the case when there are 3 digits only..
then 4,2,1 will represent all arrangements : 1,2,4; 1,4,2; 2,4,1; 2,1,4; 4,1,2; 4,2,1
That is what i meant!
