Printable Adding 9 Flash Cards
Adding 9 has the most reliable trick in addition: add ten, then take one away — 6 + 9 is 16 minus 1, so 15. The answers even show it: through 10 + 9, the ones digit is one less than the number 9 was added to (the two biggest cards, 11 + 9 = 20 and 12 + 9 = 21, carry into the twenties). These fold-over flashcards cover 1 + 9 through 12 + 9.
How to Use These Flash Cards
Say the trick aloud on every flip until it turns into plain recall: "plus ten... minus one." For 7 + 9: 17, then 16. Show the pattern in the answers — 5 + 9 = 14, 6 + 9 = 15, 7 + 9 = 16 — each answer's ones digit runs one behind. With the trick in hand, this family usually comes together quickly.
How to Cut and Fold
- Print the PDF single-sided on plain paper or light cardstock.
- Cut along the solid lines to separate the cards.
- Fold each card along the dashed center line so the answer sits behind the question, and turn the card over like a page to check.
- Optional: a dab of glue inside the fold makes a sturdy double-thick card.
Frequently Asked Questions
What is the add-ten-take-one trick?
Nine is one less than ten, so add ten and subtract one: 8 + 9 is 18 minus 1 = 17. It works on every card and is usually the first "grown-up" strategy a child falls in love with.
Why is the ones digit of the answer one less than the other number?
Because +9 is +10 (which keeps the ones digit) then take one away, which lowers it by one: 7 + 9 = 16, and 6 is one less than 7. The pattern holds through 10 + 9 and doubles as a self-check on those cards.
Should +9 facts be drilled before +6, +7, +8?
It works well early, yes — the trick is so reliable that +9 often becomes a confidence family, and the add-ten habit it builds is exactly what the make-ten strategies for +6 to +8 use.