The train is traveling 60mph. You meet two natives from different villages at a crossroads. One always lies and one always tells the truth, but you doesn't know which is which. You need to find out whether the left or right path leads to safety, but can only ask one of them a single question. Whenever a frog jumps on a lightbulb, it toggles between on and off.
All lightbulbs are initially off.
Only one of John, Alice or Frank has sweets. The methods have to be ones in which the umpires have no say. So a solution in which the pitcher just held the ball and didn't pitch wouldn't work, because the umpires could order the pitcher to pitch the ball and they would have a say. Recombinant numbers are numbers whose digits can be recombined by simple mathematical expressions to form the number themselves. Remove one square anywhere on the chessboard.