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Round vs. Square
Q Why is it better for manhole covers to be round rather than square?

A You can turn a square manhole cover sideways and drop it down the diagonal of the manhole. You cannot drop a round manhole cover down the manhole. Therefore, round manhole covers are safer and more practical than square ones.

Based on "Manhole Covers," found at
,which citesChallenging Lateral Thinking Puzzlesby Paul Sloane and Des MacHale, distributed by Cassell in the UK and by Capricorn Link in Australia.