Take a normal piece of paper, exactly 0.1 mm thick.

Fold it in half, and then in half again, and again, and again.

Do this a total of 50 times.

How thick would the final paper be (if this could be done)?

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Hint

We'll assume that we can actually fold it this many times.

Answer

Very thick indeed! The paper doubles in thickness with each fold. If we could fold it 50 times, it would be around 70 million miles thick!

1 fold would be 0.1 + 0.1 = 0.1 x 2 ^ 1 = 0.2 mm

2 folds would be 0.1 + 0.1 + 0.1 + 0.1 = 0.1 x 2 ^ 2 = 0.4 mm

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10 folds would be 0.1 x 2 ^ 10 = 102.4 mm

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50 folds would be 0.1 x 2 ^ 50 = 112,589,990,684,262.4 mm = 112,589,990.7 km (around 70 million miles).