Stretch your mind with these ingenious and perplexing puzzles! It will take all your cleverness to overlook the obvious and train your brain to think in a new and flexible way. But, in addition to building smarts, these mystifying problems are fun to figure out. Try this: An art expert went to a sale and bought a picture he knew to be worthless. Why? Check the clues if you're lost! Answer: Though the picture was worthless, he intended to reuse the fine frame it was in. 96 pages, 18 b/w illus., 4 x 5.