Heads or Tails - Puzzle of the Week

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With gloves on and blindfolded, you don't sit at the table that often.

However, this is important for the following puzzle - otherwise the solution would be too easy.

There are exactly 100 coins on the table.

37 of them with the head side up, 63 with the number side up.

You should divide these 100 coins into two groups so that the same number of coins can be seen with their heads in each group.

All 100 coins must lie flat on the table, the coins must not lie on top of each other or be stacked.

Your eyes are blindfolded and you also wear gloves so that you cannot feel the top of the coins with your fingers.

So that the task is not that difficult, you can turn over as many of the 100 coins as you want, i.e. change the head and the number side.

But as I said: you can neither see nor feel the sides of the coin.

How do you divide the 100 coins into two groups?

You slide 37 coins on one side of the table and 63 on the other.

The choice of coins is arbitrary.

Then turn over all the coins of the group of 37 and you're done.

Why does the trick work?

We assume that in the randomly chosen group of 63 there are

coins upside down and

with tails.

We don't know the

number

, but that doesn't matter, as we'll see in a moment.

In the group of

there must be

coins with heads, because at the beginning there were a total of 37 coins with the heads facing up on the table.

That is why there are

coins

in the 37 group

with the number side up.

If you turn over all the coins in group

, you get

heads and

tails

.

With this the task is solved, because in each group there are

coins with the heads up.

I discovered this very nice puzzle on the website matheboard.de.

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