Monday 24 November 2014

Cards inside envelopes

Here is a combinatorics related puzzle.
We have 6 envelopes numbered from 1 to 6.  Likewise we have 6 cards numbered 1 to 6.
You have to put each card in one envelope(it would have only 1 card), such that the card number is never the same as the number of the envelope its placed in.

Question 1: How many different ways can it be done in?

Question: If card # 1 is to be always placed in envelope #2, other constraints remaining same, how many ways are possible now?

Will post my solution in some days.

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