Enthrall math marvelers of all ages with these double-sided multi-colored puzzles; Change Equivalence (24 reversible puzzles) with two levels of difficulty, Dollar Equivalence (24 reversible puzzles), Percent Equivalence (20 reversible puzzles), Cross Math Addition & Subtraction (72 reversible puzzles) and Cross Math Multiplication & Division (24 Reversible Puzzles). Guaranteed to intrigue everyone who uses them!