Lay out six matches in the way depicted in the illustration. The objective is to shift one match without displacing the others so that the resulting arrangement would represent an arithmetical fraction equal to 1. You are not allowed to move the match forming the horizontal fraction bar.
In the 1916 issue of Strand Magazine, Henry Ernest Dudeney wrote that a French correspondent sent him this matchstick puzzle but the solution was not given to him. Hence, he solved it himself.
Dudeney said that he’s certain that the solution to this puzzle was the same as his solution.
You can see that one of the I in VII is shifted to form a square root or radical sign. The square root of 1 is 1 and 1 divided 1 is equal to 1.
This is one of the best “easy” matchstick puzzles I have ever seen. I’m not sure if I would be able to figure this out if someone challenges me to solve it without prior knowledge of the solution.