+13 +185 Jun 25, 2020
+133 +865 +865 +163 Four letters (numbered 1, 2, 3, 4, 5) are to be placed in four envelopes (numbered 1, 2, 3, 4, 5), so that no letter goes into the right envlope. Also, letter 1 goes into envlope 2. How many ways can the other letters be placed?
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