A friend purchased "The World's Worst Riddles", a slim book at a second-hand bookshop.

Published in 1968, its Introduction says that by "worst", it might mean "best".

However... here are some for mathematicians:

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Q: A man bought 90 hens. He placed 30 on the first perch, 30 on the second, and the remaining 30 on the top perch. How many hens did he own? A: Only the ones on the first perch because the others were on higher perches (hire purchase).

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Q: If it took eight men eight hours to build a brick fence how long would it take five men to build it? A: None, because the eight men have done the work.

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Q: If six magpies are sitting on a fence and one is shot, how many are left? A: None, because the others flew away.

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Q: Two's company, three's a crowd but what is four and five? A: Nine.

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