Henry Ernest Dudeney/Puzzles and Curious Problems/344 - Coin and Hole/Solution

Puzzles and Curious Problems by Henry Ernest Dudeney: $344$

Coin and Hole

We have before us a specimen of every coin which was current in Britain in $1930$.

And we have a sheet of paper with a circular hole cut in it $\tfrac 3 4$ of an inch in diameter.

What is the largest coin I can pass through that hole without tearing the paper?

Solution

Strange thought it may appear, the half-crown may be passed through the small hole (about the size of a sixpence) without tearing the paper.

This is the largest coin that can be used.

First fold the paper across the centre of the hole and drop the coin into the fold.

Then, holding the paper at $A$ and $B$, bring the hands together upwards, and the coin may be shaken through the hole.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Solutions: $344$. -- Coin and Hole
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $527$. Coin and Hole