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Logical Puzzles Hard 3 min

Seven cards numbered 1 through 7 are placed face down. If card 1 is immediately before card 2 and card 3 is immediately before card 4, how many arrangements are possible?

Hint
Treat 1-2 and 3-4 as two blocks.

Answer

120.

Explanation

The two blocks plus cards 5, 6 and 7 give five objects. They can be arranged in 5! ways. Each block has a fixed internal order.

Step-by-Step Solution

Objects = [1-2], [3-4], 5, 6, 7.
Number of arrangements = 5! = 120.
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