Four decks of flash cards: addition, subtraction, multiplication, and division. 231 double-sided cards, for 462 total practice problems. Children can reinforce essential math skills with parents or by themselves. Great for meeting Common Core math memorization and fluency requirements. Practice addition and subtraction through 20, and multiplication and division through 100. Comes with a ring holder that fits in the holes punched in each card for easy organization. Flash Card Set box measures 7.2" wide x 6" high x 2.5" deep (18.3 cm wide x 15.2 cm high x 6.4 cm deep). Grades K–3, and beyond.