A set of 20 x 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.