10-Complement Rule Drills

Course: Abacus for Children — Level 2

Practice Sheet · Premium

4 pages of 10-complement rule drills with carry explanation and technique column. 60 problems.

Abacus Progress Pack — 10-Complement Rule Drills

60 problems across 4 pages. The 10-complement rule is used when the ones rod overflows: carry 1 bead to the tens rod and remove the 10-complement from the ones rod.

The 10-Complement Pairs

1+9 = 102+8 = 103+7 = 104+6 = 105+5 = 10

Carry Explanation

When adding makes the ones rod exceed 9: (1) add 1 bead on the tens rod, (2) subtract the 10-complement from the ones rod. When subtracting and the ones rod does not have enough: (1) remove 1 bead from the tens rod, (2) add the 10-complement to the ones rod.

Page 1 of 4 — Adding with 9s and 8s

Focus on 10-complement pairs involving 9 (complement = 1) and 8 (complement = 2).

#	Problem	Technique Used
1	9 + 1	Direct (no carry)
2	9 + 2	10-rule: +10 then -8
3	9 + 3	10-rule: +10 then -7
4	9 + 4	10-rule: +10 then -6
5	9 + 5	10-rule: +10 then -5
6	9 + 6	10-rule: +10 then -4
7	9 + 7	10-rule: +10 then -3
8	9 + 8	10-rule: +10 then -2
9	9 + 9	10-rule: +10 then -1
10	8 + 2	Direct (no carry)
11	8 + 3	10-rule: +10 then -7
12	8 + 4	10-rule: +10 then -6
13	8 + 5	10-rule: +10 then -5
14	8 + 6	10-rule: +10 then -4
15	8 + 7	10-rule: +10 then -3

Page 2 of 4 — Adding with 7s, 6s, and 5s

Focus on 10-complement pairs involving 7 (complement = 3), 6 (complement = 4), and 5 (complement = 5).

#	Problem	Technique Used
16	7 + 3	Direct (no carry)
17	7 + 4	10-rule: +10 then -6
18	7 + 5	10-rule: +10 then -5
19	7 + 6	10-rule: +10 then -4
20	7 + 7	10-rule: +10 then -3
21	7 + 8	10-rule: +10 then -2
22	7 + 9	10-rule: +10 then -1
23	6 + 4	Direct (no carry)
24	6 + 5	10-rule: +10 then -5
25	6 + 6	10-rule: +10 then -4
26	6 + 7	10-rule: +10 then -3
27	6 + 8	10-rule: +10 then -2
28	6 + 9	10-rule: +10 then -1
29	5 + 5	Direct (no carry)
30	5 + 6	10-rule: +10 then -4

Page 3 of 4 — 10-Complement Subtraction

When subtracting and the ones rod does not have enough beads, borrow from the tens rod: remove 1 tens bead and add the 10-complement to ones.

#	Problem	Technique Used
31	11 - 9	10-rule: -10 then +1
32	11 - 8	10-rule: -10 then +2
33	11 - 7	10-rule: -10 then +3
34	11 - 6	10-rule: -10 then +4
35	12 - 9	10-rule: -10 then +1
36	12 - 8	10-rule: -10 then +2
37	12 - 7	10-rule: -10 then +3
38	13 - 9	10-rule: -10 then +1
39	13 - 8	10-rule: -10 then +2
40	13 - 7	10-rule: -10 then +3
41	14 - 9	10-rule: -10 then +1
42	14 - 8	10-rule: -10 then +2
43	15 - 9	10-rule: -10 then +1
44	15 - 8	10-rule: -10 then +2
45	16 - 9	10-rule: -10 then +1

Page 4 of 4 — Mixed Speed Drill (3 minutes)

No technique hints. Write the answer AND the technique you used.

#	Problem	Answer	Technique Used
46	9 + 6
47	11 - 7
48	8 + 5
49	14 - 9
50	7 + 7
51	13 - 8
52	6 + 8
53	12 - 6
54	9 + 9
55	15 - 7
56	8 + 8
57	11 - 5
58	7 + 6
59	16 - 9
60	6 + 9

Score

54+ = Excellent · 42-53 = Good · below 42 = Review 10-complement pairs

___ / 60

Page 1 (9s,8s): ___ / 15

Page 2 (7s,6s,5s): ___ / 15

Page 3 (sub): ___ / 15

Page 4 (speed): ___ / 15

Part of these learning packs

Abacus Progress Pack

16 printable pages for Levels 2–3 — complement rules, carry/borrow operations, and error-checking templates with parent answer keys

One page per complement pair (1↔9, 2↔8, 3↔7, 4↔6). The foundation for all carry/borrow.

These packs include this resource alongside other printables, tools, and study guides — curated for a specific goal. View all packs →

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