This is a wonderful puzzle that I saw today after a long time. I was asked this puzzle in an interview in Microsoft back in 1994 March – yes it has been a long time! I saw it today in a Martin Gardner book – The Colossal Book of Short Puzzles and Problems.
Here is the puzzle:
An oil well being drilled in a flat prairie country struck pay sand at an underground spot exactly 21,000 feet from one corner of a rectangular plot of farmland, 18,000 feet from the opposite corner, and 6,000 feet from a third corner. How far is the underground spot from the fourth corner?
As always, please send your answers as comments within the blog (preferred), or send an e-mail to firstname.lastname@example.org. Please do share the puzzle with others if you like, and please also send puzzles that you have come across that you think I can share in this blog.