Adding up to 20

Grade 1 · Level 3 · Sheet 1

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the answers

Name Date

Free from tutor.in4me.app · 1.OA.B.4, 1.OA.D.8, 1.OA.C.6, 1.OA.A.1 · Five minutes a day online, and the difficulty follows your child.

1.
?+5=19
2.
?+8=16
3.
12+?=17
4.
?+5=7
5.
?+4=14
6.
?+11=17
7.
1+?=13
8.
9+?=19
9.
?+2=7
10.
?+4=19
11.
18+?=19
12.
11+?=17

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1.14
2.8
3.5
4.2
5.10
6.6
7.12
8.10
9.5
10.15
11.1
12.6

The mistakes behind most wrong answers

A wrong answer in adding up to 20 is rarely random. These are the ones that come up most often, each on a real problem — worth knowing before you mark a sheet, because the fix for each is different.

18+?=20
The answer is 2. A child who answers 3 probably counted one too many or too few.
?+2=7
The answer is 5. A child who answers 2 probably answered with one of the numbers shown.
?+1=20
The answer is 19. A child who answers 20 probably added instead of taking away.
7+12=?
The answer is 19. A child who answers 5 probably took away instead of adding.

In the app, every wrong answer is matched against mistakes like these, and the weekly email tells you which one your child keeps making — in those words, not as a percentage.

Answer key · Adding up to 20 · Level 3 · Sheet 1

The mistakes behind most wrong answers