There are ten coins on a table. Five are heads and five are tails. You have been blindfolded, and your task is t create two piles of coins that have the same number of heads-up coins. No, you can't tell the heads and tails sides by feeling them. How do you achieve this task?

Solution

Make two piles of 5 coins each. Flip all the coins in one pile.

Let's say that one pile has H-H-H-T-T. Then the other pile will be the complement of this pile: T-T-T-H-H. When you flip all the coins in the second pile, it will be just like the first pile.

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