Every addition fact from 1+1 through 10+10 — 55 cards, duplicates removed. These are the facts K–2 programs drill toward automaticity, because everything after (subtraction, multi-digit addition, mental math) leans on them.
Two clusters do the heavy lifting: doubles (6+6, 7+7, 8+8) and make-ten pairs (7+3, 6+4, 8+2). Kids who own those two clusters derive the rest fast — 7+8 is "7+7 and one more." If a learner is early in the journey, edit the deck down to doubles and tens-pairs first, then rebuild to the full 55.
Every card read backwards is a subtraction fact — 9+6=15 contains 15−6=9. Once the addition deck is fluent, flip the drill: read the back (15), have the learner name pairs that make it. Cheaper than a second deck and better math.
More ready-made sets: Times Tables Flashcards (2–12) · Multiplication Flashcards (1–10) · see all