Puzzle makers: Try to make each puzzle have a unique solution. Chess puzzles in which making a different move has no real effect on the outcome (e.g. it doesn't matter if a king on g1 moves to f1 or h1) are fine, as are "fill in the grid" puzzles where a different orientation is still correct, but you shouldn't be making puzzles where making major differences from what you have still results in a correct answer.
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I'll start with a math puzzle.
Timmy, who is a gambling addict, enters a casino with $50 at 7:00 PM. He loses $20 in his first five minutes, but in the next five minutes he is able to make $15 of it back. He loses $20 more in his third five minutes, wins $15 back in his fourth five minutes, and so on in that cycle. At what time will he run out of money?