From the designs on Mondrian's paintings to the elegant organization of mathematical sequences, these puzzles all involve the wonderful world of patterns. Some use colors, others feature letters, and still more focus on shapes, but all offer plenty of entertainment. Suppose you have a supply of beads in red, green, and yellow, and are making them into necklaces that consist of five beads each. If each necklace has two beads of one color, two of a second, and one of a third, how many distinct necklaces can you create? Or, for another kind of pattern, try solving anagrams and deciphering cryptograms to unearth secret messages. Fold ten flaps into a five-by-five square to form a pinwheel pattern. Every problem is intriguing.