Subtraction Flash Cards: Teach subtraction with numbers to 10, to 20 and to 100. This value pack of flash cards includes 3 sets of 54 cards for teaching subtraction. Covers subtraction under 10, under 20 and under 100. Visual arrays are provided to help children see the mathematical relationships. Teaches fast, automatic recall. A perfect activity for independent or guided learning.Details:8.1" x 3.5" x 0.9" package size3 flashcard sets, 162 cardsFor ages 5 and up