The number bonds to 20 are 11 pairs, from 0 and 20 to 10 and 10. Each one is a bond of 10 with a ten added to one part. Print one pair, or all 11 on one sheet.
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How 6 bonds of 10 give 11 pairs of 20
Take 3 and 7. Add a ten to the 7 and you have 3 and 17. Add it to the 3 and you have 7 and 13. 5 bonds of 10 give 2 pairs of 20 like this. 5 and 5 gives only 5 and 15, so the total is 11.
Spot a pair of 20 by its ones digits
In 3 and 17 the ones digits are 3 and 7, which make 10, and the ten in 17 makes the second 10. That check works for 9 of the 11 pairs. The other 2 are 0 and 20 and 10 and 10, where both ones digits are 0.
The opening set prints as a number bonds to 20 worksheet: 12 bonds, with the answer key as page 2.
If the partner of 3 comes back as 7, the ten was dropped: try a double ten frame sheet.
Helper hidden: all 11 pairs is the check at the end: the bond of 10 is no longer drawn.
Questions and answers
What are the number bonds to 20?
They are 11 pairs: 0 and 20, 1 and 19, 2 and 18, 3 and 17, 4 and 16, 5 and 15, 6 and 14, 7 and 13, 8 and 12, 9 and 11, and 10 and 10.
What grade learns number bonds to 20?
Grades 1 and 2 in the US, years 1 and 2 in England. The Common Core has grade 1 add and subtract within 20 (1.OA.6) and grade 2 do so fluently (2.OA.2). England wants the bonds to 20 known by the end of year 2.
How do number bonds to 20 help with subtraction?
Every pair is also a subtraction from 20. Know 3 and 17, and 20 − 3 = 17 and 20 − 17 = 3 follow with no counting back. England's year 1 curriculum lists number bonds and related subtraction facts within 20 in one line.
All 28 practice sets
The 11 pairs that make 20 11
0 and 20From 0 and 10, with the ten added to the 10. One part is nothing and the other is everything: 0 + 20 = 20, 20 − 0 = 20 and 20 − 20 = 0. England's year 1 guidance puts the effect of adding or subtracting 0 inside its work on bonds to 10 and 20.
1 and 19From 1 and 9, with the ten added to the 9. 19 is one step back from 20, so this pair is counting as much as adding: 19 + 1 = 20 and 20 − 1 = 19. No pair of 20 has a larger part, apart from the 20 in 0 and 20.
2 and 18From 2 and 8, with the ten added to the 8. The Common Core's own example of a teen number is this part: 18 = 10 + 8 (K.NBT.1). Read 18 that way and the pair is 2 + 8 + 10 = 20.
3 and 17From 3 and 7, with the ten added to the 7. The ones digits, 3 and 7, make one ten, and the 1 in 17 is the other: 3 + 17 = 3 + 7 + 10 = 20. Both parts are odd.
Show all 28 practice sets (24 more)
The 11 pairs that make 20, continued
4 and 16From 4 and 6, with the ten added to the 6. As a subtraction it never touches the second ten: 10 − 4 = 6, so 20 − 4 = 16. Both parts are even.
5 and 15From 5 and 5, the only bond of 10 that gives one pair of 20 and not two: add the ten to either 5 and the result is the same. A double ten frame is 4 rows of 5 squares, and this pair is 1 row and 3 rows.
6 and 14From 6 and 4, with the ten added to the 4. From here on the one-digit part is the larger half of its bond of 10, so the teen part is a small one: 14 is only 4 past 10. 6 + 14 = 6 + 4 + 10 = 20.
7 and 13From 7 and 3, with the ten added to the 3. Add the 7 to the 13 and the ones make a new ten: 13 + 7 = 10 + 3 + 7 = 10 + 10 = 20. Texas names the strategy making 10 (1.3(D)).
8 and 12From 8 and 2, with the ten added to the 2. For 20 − 12, think what goes with 12 to make 20: 12 + 8 = 20, so 20 − 12 = 8. The Common Core calls this subtraction as an unknown-addend problem (1.OA.4).
9 and 11From 9 and 1, with the ten added to the 1. The two parts are as close as they can be without being equal. Move 1 from the 11 to the 9 and the pair is 10 and 10: 9 + 11 = 10 + 10 = 20.
10 and 10From 10 and 0, with the ten added to the 0. The only double among the pairs of 20, the only pair with no one-digit part, and the only one with no turn-around, so it can be asked 3 ways, not 6. 10 + 10 = 20.
Two pairs from one bond of 10 5
From 0 and 10: 0 and 20, double 10Add the ten to the 10 and the pair is 0 and 20. Add it to the 0 and the pair is double 10. The first and the last of the 11 pairs come from one bond, and they are the only pairs whose ones digits are both 0.
From 1 and 9: 1 and 19, 9 and 11One bond, two pairs that look nothing alike: 19 sits next to 20 and 11 sits next to 10. 1 + 19 = 20 and 9 + 11 = 20.
From 2 and 8: 2 and 18, 8 and 12All four parts are even. Halve them and you are back among the pairs of 10: 1 and 9, 4 and 6. 2 + 18 = 20 and 8 + 12 = 20.
From 3 and 7: 3 and 17, 7 and 13All four parts are odd, and in both pairs the ones digits are 3 and 7. That is the check for any pair of 20 with a teen part: the ones digits make 10. 3 + 17 = 20 and 7 + 13 = 20.
From 4 and 6: 4 and 16, 6 and 14The pairs on either side of 5 and 15. The one-digit part goes up by 2, from 4 to 6, and the teen part comes down by 2, from 16 to 14, so the whole stays at 20.
On a double ten frame 3
Double ten frame: how many more to make 20?Two frames of 2 rows of 5 squares show some counters, over a bond with 20 on top. The first frame fills before the second starts. The pupil writes the counters as one part and the empty squares as the other. 21 different pictures, from no counters (20 more) to 20 counters (0 more).
First frame full: teen part drawnThe counters show 11 to 19, so the first frame is full every time and only the second has empty squares to count. That is a bond of 10 with a full ten parked beside it. 9 pictures.
Second frame empty: one-digit part drawnThe counters show 1 to 9, all in the first frame. The partner is that frame's empty squares and the whole second frame: for 3 counters, 7 + 10 = 17. 9 pictures.
Drills with all 11 pairs 9
All 11 pairs that make 200 and 20, 1 and 19, 2 and 18, 3 and 17, 4 and 16, 5 and 15, 6 and 14, 7 and 13, 8 and 12, 9 and 11, 10 and 10. One part is given, its partner is missing, and the bond of 10 behind the pair is drawn beside it.
Even pairs of 200 and 20, 2 and 18, 4 and 16, 6 and 14, 8 and 12, 10 and 10. Halve every number and these 6 pairs are the 6 pairs of 10, so a pupil who knows 3 and 7 can double it to 6 and 14.
Helper hidden: all 11 pairsThe same 11 pairs with nothing drawn beside them. Print it straight after a helped sheet and compare the two scores: the gap is how much work the bond of 10 was doing.
Odd pairs of 201 and 19, 3 and 17, 5 and 15, 7 and 13, 9 and 11. 20 is even, so an odd part always has an odd partner. 5 pairs and no double, so turned round they make 10 questions.
One-digit part givenThe given part is 1 to 9 and the answer is always a teen number, 11 to 19. Find the partner to 10, then say ten more: for 6 that is 4, then 14. 9 questions.
Pairs of 10 and pairs of 20 mixedSome bonds have 10 on top and some have 20, 17 pairs in all. With 3 given, the partner is 7 under a 10 and 17 under a 20, so the top circle has to be read first.
Teen part givenThe given part is 11 to 19 and the answer is always one digit. Cover the ten and it is a bond of 10: for 14, ask what goes with 4. 9 questions.
Turn-arounds of 20Each pair can be asked from either part, which makes 21 questions from 11 pairs: 2 × 11 − 1 = 21, because 10 and 10 turned round is still 10 and 10. A sheet prints 12 of them. If 17 + 3 = 20 is known, so is 3 + 17 = 20.
Whole missing: is it 10 or 20?Both parts are given and the top circle is empty: 3 and 7, or 3 and 17? Zero is left out, so every pair of 10 has two one-digit parts and every pair of 20 has a two-digit part. 15 pairs.
How this list was compiled: Own work: every pair, every count of pairs and ways, the halving, parity and ones-digit statements and the ladder statement were computed and re-derived a second way on 2026-09-19. Definition of a number bond and bonds learned in sets with a round sum such as 10 or 20: Wikipedia, Number bond, https://en.wikipedia.org/wiki/Number_bond (checked 2026-09-19). Grade anchors read in the full standards texts on 2026-09-19: Common Core State Standards for Mathematics, CCSSO copy, https://learning.ccsso.org/wp-content/uploads/2022/11/Math_Standards1.pdf; Texas Essential Knowledge and Skills, 19 TAC chapter 111 subchapter A, https://tea.texas.gov/sites/default/files/ch111a.pdf; National curriculum in England, mathematics programmes of study, https://www.gov.uk/government/publications/national-curriculum-in-england-mathematics-programmes-of-study/national-curriculum-in-england-mathematics-programmes-of-study (checked 2026-09-19). Lines quoted here: CCSS K.NBT.1 (18 = 10 + 8), K.OA.4, 1.NBT.2 (11 to 19 are a ten and some ones; 20 is two tens), 1.OA.3, 1.OA.4, 1.OA.5, 1.OA.6, 2.OA.2; TEKS 1.3(D), 1.5(G), 2.4(A); England year 1 (number bonds and related subtraction facts within 20; the effect of adding or subtracting 0) and year 2 (know the number bonds to 20; facts to 20 fluently). Neither the Common Core nor the Texas standards name the ten frame, so a frame is described only as what is drawn: 2 rows of 5 squares. The standards texts and the Wikipedia articles named here were read again on 2026-10-03. Licence: own work