Connecting Number Rods Work CardsA set of A5 (5. 8" x 8. 3") cards designed to be used with connecting number rods using numbers 1 20 in the question. There are 10 addition and 10 subtraction color coded cards. Each card has a question on the front and the answer with images of the connecting number rods on the reverse. Any card can be completed using the connecting number rods 64 piece set (sold separately). Each set of 20 includes 10 addition and 10 subtraction color coded cards.