The common wooden matchstick, with its brightly colored tip and sturdy box, has inspired tricks and puzzles ever since it was invented. Here's a collection of the most baffling matchstick puzzles of all time, from the six riddles of the nine squares to the astonishing effect of the matchstick telegraph. Can you build a bridge with just two matches? Can you balance matchstick equations? Can you calculate how many matches you would need to cover the...