Math Plane - Hidden Message Math puzzles 20 Hidden Messages. Use basic operations, logic, and other math knowledge to find the hidden message. (Front Cover) .PDF file (77 pages) $ 5.95 In stock Hidden Messages II 19 Hidden Messages. Utilizes decimals, Fractions, Roman Numerals, Probability, Word Problems, Slope, GCF/LCM, Area, shapes, and more! .PDF file (58 pages) $ 5.95 In stock