Kakuro is the next hot puzzle craze, and everyone can give it a try with this new, multilevel series.These language-free number puzzles use pure logic and require just simple arithmetic to solve.So, in addition to being fun, they help develop your powers of deduction and reasoning.Beginners can get started - and more experienced solvers hone their skills - with these perfectly tiered "belt" books, each containing 150 kakuros.They take their cue from the belt colors in martial arts: white is for novices, green for intermediates, brown for very accomplished players, and black for those consummate experts who crave a challenge.