24 − 12A double undone: 12 + 12 = 24, so taking one 12 away leaves 12.
+ and − within 10 66
0 + 00 + 0 = 0. Its partner on the minus side: 0 − 0 = 0.
0 + 10 + 1 = 1. Its partners on the minus side: 1 − 1 = 0 and 1 − 0 = 1.
0 + 20 + 2 = 2. Its partners on the minus side: 2 − 2 = 0 and 2 − 0 = 2.
0 + 30 + 3 = 3. Its partners on the minus side: 3 − 3 = 0 and 3 − 0 = 3.
0 + 40 + 4 = 4. Its partners on the minus side: 4 − 4 = 0 and 4 − 0 = 4.
0 + 50 + 5 = 5. Its partners on the minus side: 5 − 5 = 0 and 5 − 0 = 5.
0 + 60 + 6 = 6. Its partners on the minus side: 6 − 6 = 0 and 6 − 0 = 6.
0 + 70 + 7 = 7. Its partners on the minus side: 7 − 7 = 0 and 7 − 0 = 7.
0 + 80 + 8 = 8. Its partners on the minus side: 8 − 8 = 0 and 8 − 0 = 8.
0 + 90 + 9 = 9. Its partners on the minus side: 9 − 9 = 0 and 9 − 0 = 9.
0 + 100 + 10 = 10. Its partners on the minus side: 10 − 10 = 0 and 10 − 0 = 10.
1 + 01 + 0 = 1. Its partners on the minus side: 1 − 0 = 1 and 1 − 1 = 0.
1 + 11 + 1 = 2. Its partner on the minus side: 2 − 1 = 1.
1 + 21 + 2 = 3. Its partners on the minus side: 3 − 2 = 1 and 3 − 1 = 2.
1 + 31 + 3 = 4. Its partners on the minus side: 4 − 3 = 1 and 4 − 1 = 3.
1 + 41 + 4 = 5. Its partners on the minus side: 5 − 4 = 1 and 5 − 1 = 4.
1 + 51 + 5 = 6. Its partners on the minus side: 6 − 5 = 1 and 6 − 1 = 5.
1 + 61 + 6 = 7. Its partners on the minus side: 7 − 6 = 1 and 7 − 1 = 6.
1 + 71 + 7 = 8. Its partners on the minus side: 8 − 7 = 1 and 8 − 1 = 7.
1 + 81 + 8 = 9. Its partners on the minus side: 9 − 8 = 1 and 9 − 1 = 8.
1 + 91 + 9 = 10. Its partners on the minus side: 10 − 9 = 1 and 10 − 1 = 9.
2 + 02 + 0 = 2. Its partners on the minus side: 2 − 0 = 2 and 2 − 2 = 0.
2 + 12 + 1 = 3. Its partners on the minus side: 3 − 1 = 2 and 3 − 2 = 1.
2 + 22 + 2 = 4. Its partner on the minus side: 4 − 2 = 2.
2 + 32 + 3 = 5. Its partners on the minus side: 5 − 3 = 2 and 5 − 2 = 3.
2 + 42 + 4 = 6. Its partners on the minus side: 6 − 4 = 2 and 6 − 2 = 4.
2 + 52 + 5 = 7. Its partners on the minus side: 7 − 5 = 2 and 7 − 2 = 5.
2 + 62 + 6 = 8. Its partners on the minus side: 8 − 6 = 2 and 8 − 2 = 6.
2 + 72 + 7 = 9. Its partners on the minus side: 9 − 7 = 2 and 9 − 2 = 7.
2 + 82 + 8 = 10. Its partners on the minus side: 10 − 8 = 2 and 10 − 2 = 8.
3 + 03 + 0 = 3. Its partners on the minus side: 3 − 0 = 3 and 3 − 3 = 0.
3 + 13 + 1 = 4. Its partners on the minus side: 4 − 1 = 3 and 4 − 3 = 1.
3 + 23 + 2 = 5. Its partners on the minus side: 5 − 2 = 3 and 5 − 3 = 2.
3 + 33 + 3 = 6. Its partner on the minus side: 6 − 3 = 3.
3 + 43 + 4 = 7. Its partners on the minus side: 7 − 4 = 3 and 7 − 3 = 4.
3 + 53 + 5 = 8. Its partners on the minus side: 8 − 5 = 3 and 8 − 3 = 5.
3 + 63 + 6 = 9. Its partners on the minus side: 9 − 6 = 3 and 9 − 3 = 6.
3 + 73 + 7 = 10. Its partners on the minus side: 10 − 7 = 3 and 10 − 3 = 7.
4 + 04 + 0 = 4. Its partners on the minus side: 4 − 0 = 4 and 4 − 4 = 0.
4 + 14 + 1 = 5. Its partners on the minus side: 5 − 1 = 4 and 5 − 4 = 1.
4 + 24 + 2 = 6. Its partners on the minus side: 6 − 2 = 4 and 6 − 4 = 2.
4 + 34 + 3 = 7. Its partners on the minus side: 7 − 3 = 4 and 7 − 4 = 3.
4 + 44 + 4 = 8. Its partner on the minus side: 8 − 4 = 4.
4 + 54 + 5 = 9. Its partners on the minus side: 9 − 5 = 4 and 9 − 4 = 5.
4 + 64 + 6 = 10. Its partners on the minus side: 10 − 6 = 4 and 10 − 4 = 6.
5 + 05 + 0 = 5. Its partners on the minus side: 5 − 0 = 5 and 5 − 5 = 0.
5 + 15 + 1 = 6. Its partners on the minus side: 6 − 1 = 5 and 6 − 5 = 1.
5 + 25 + 2 = 7. Its partners on the minus side: 7 − 2 = 5 and 7 − 5 = 2.
5 + 35 + 3 = 8. Its partners on the minus side: 8 − 3 = 5 and 8 − 5 = 3.
5 + 45 + 4 = 9. Its partners on the minus side: 9 − 4 = 5 and 9 − 5 = 4.
5 + 55 + 5 = 10. Its partner on the minus side: 10 − 5 = 5.
6 + 06 + 0 = 6. Its partners on the minus side: 6 − 0 = 6 and 6 − 6 = 0.
6 + 16 + 1 = 7. Its partners on the minus side: 7 − 1 = 6 and 7 − 6 = 1.
6 + 26 + 2 = 8. Its partners on the minus side: 8 − 2 = 6 and 8 − 6 = 2.
6 + 36 + 3 = 9. Its partners on the minus side: 9 − 3 = 6 and 9 − 6 = 3.
6 + 46 + 4 = 10. Its partners on the minus side: 10 − 4 = 6 and 10 − 6 = 4.
7 + 07 + 0 = 7. Its partners on the minus side: 7 − 0 = 7 and 7 − 7 = 0.
7 + 17 + 1 = 8. Its partners on the minus side: 8 − 1 = 7 and 8 − 7 = 1.
7 + 27 + 2 = 9. Its partners on the minus side: 9 − 2 = 7 and 9 − 7 = 2.
7 + 37 + 3 = 10. Its partners on the minus side: 10 − 3 = 7 and 10 − 7 = 3.
8 + 08 + 0 = 8. Its partners on the minus side: 8 − 0 = 8 and 8 − 8 = 0.
8 + 18 + 1 = 9. Its partners on the minus side: 9 − 1 = 8 and 9 − 8 = 1.
8 + 28 + 2 = 10. Its partners on the minus side: 10 − 2 = 8 and 10 − 8 = 2.
9 + 09 + 0 = 9. Its partners on the minus side: 9 − 0 = 9 and 9 − 9 = 0.
9 + 19 + 1 = 10. Its partners on the minus side: 10 − 1 = 9 and 10 − 9 = 1.
10 + 010 + 0 = 10. Its partners on the minus side: 10 − 0 = 10 and 10 − 10 = 0.
How this list was compiled: Own work. The deck undoes every addition fact from 0 + 0 to 12 + 12: the number taken away and the answer each run from 0 to 12, so the starting number runs from 0 to 24 and no answer is negative. One more set, + and − within 10, puts the 66 addition facts with sums of 10 or less beside the 66 subtraction facts within 10, 132 cards; those sums were computed and checked by integer arithmetic on 2026-09-20, which brings the deck to 235 cards. 13 x 13 = 169 cards; every difference, every line of working, the addition partner printed on every back and the size of every set was checked by integer arithmetic on 2026-09-19: 13 cards in each − set, 21 within 5, 66 within 10, 11 take from ten, 13 doubles undone, 26 answers of 1 or 2, 36 that cross ten (start above ten, answer below it), 100 basic facts and 159 within 20. The strategies on the backs are the ones named in Common Core standards 1.OA.4 (subtraction as an unknown-addend problem, 10 take away 8 found as the number that makes 10 when added to 8) and 1.OA.6 (decomposing a number leading to a ten, 13 take away 4 worked as 13, 10, 9, and using a known addition fact); K.OA.5 asks for fluency within 5, 1.OA.6 within 10 and 2.OA.2 within 20. Read in the standards document hosted by CCSSO, https://learning.ccsso.org/wp-content/uploads/2022/11/Math_Standards1.pdf, checked 2026-09-19. The words minuend, subtrahend and difference, counting up from the smaller number, the fact that swapping the two numbers changes the answer, and that a smaller number minus a larger one is not a natural number were checked against Wikipedia, Subtraction, https://en.wikipedia.org/wiki/Subtraction, checked 2026-09-19. Licence: own work
How it works
These subtraction flash cards undo every addition fact up to 12 + 12: 169 cards from 0 − 0 to 24 − 12, no answer below zero. One side shows 15 − 7. The other gives 8, a way to work it out, and 8 + 7 = 15.
Read the full guide
What the subtraction sets hold
− 0 to − 12 have 13 cards apiece: − 7 runs from 7 − 7 to 19 − 7. Within 5 holds 21 facts, Within 10 66 and Within 20 159. Take from ten runs from 10 − 0 to 10 − 10, Doubles undone has 13 like 16 − 8, and Cross ten has 36 like 13 − 5.
Addition and subtraction flash cards in one set
+ and − within 10 shuffles the 66 subtraction facts within 10 with the 66 addition facts whose sums stop at 10. The back of 3 + 4 names its partners, 7 − 4 and 7 − 3. Past 10, print − 7 here and + 7 from the addition flash cards.
Thirteen cards overflow a sheet of 12, so 19 − 7 lands alone on sheet 2 of the − 7 set.
When a child counts back on fingers for 12 − 9, ask what goes with 9 to make 12: up 1 to 10, then 2 more.
Order matters: 7 − 3 is 4, but 3 − 7 falls below zero, which is why the deck has no such card.
Questions and answers
Why does every back show an addition fact?
Subtraction is addition run backward: 15 − 7 = 8 exactly when 8 + 7 = 15. The Common Core grade 1 standards describe subtraction as finding an unknown addend, so a child who knows 8 + 7 already owns 15 − 7.
Which sets fit which grade?
By our reading of the Common Core, not an official alignment, kindergarten aims for fluency within 5, grade 1 within 10 and grade 2 within 20. The Within 5, Within 10 and Within 20 sets match. Ten cards, such as 24 − 12, start above 20.
Are there addition and subtraction flashcards to print as one set?
Yes. Pick + and − within 10 under Show only, turn a card and press Print cards: 132 cards on 11 sheets of paper, 66 of each operation. One − set takes 2 sheets, and All, the 169 subtraction facts, takes 15.