Adding within 20 is where children move from counting on to real strategies such as making ten and using doubles. By the end of second grade, students are expected to know all sums of two one-digit numbers from memory.
Grades 1–2
Common Core 1.OA.C.6, 2.OA.B.2
Answer key included
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NameDate
Addition Within 20
Score / 30
Add.
1.2+6=
2.3+11=
3.0+15=
4.14+3=
5.15+2=
6.8+1=
7.7+12=
8.2+11=
9.12+2=
10.0+16=
11.6+6=
12.1+3=
13.10+2=
14.1+10=
15.13+2=
16.19+1=
17.15+4=
18.0+7=
19.11+9=
20.10+7=
21.1+16=
22.4+6=
23.0+12=
24.5+4=
25.3+15=
26.0+8=
27.2+9=
28.1+18=
29.10+6=
30.6+0=
Answer keyAddition Within 20
Add.
1.2+6=8
2.3+11=14
3.0+15=15
4.14+3=17
5.15+2=17
6.8+1=9
7.7+12=19
8.2+11=13
9.12+2=14
10.0+16=16
11.6+6=12
12.1+3=4
13.10+2=12
14.1+10=11
15.13+2=15
16.19+1=20
17.15+4=19
18.0+7=7
19.11+9=20
20.10+7=17
21.1+16=17
22.4+6=10
23.0+12=12
24.5+4=9
25.3+15=18
26.0+8=8
27.2+9=11
28.1+18=19
29.10+6=16
30.6+0=6
What's on this worksheet
Two numbers from 0 to 20 with sums up to 20. Many problems cross ten, like 8 + 7 or 9 + 6. Each sheet comes with an answer key on a separate page.
Teaching tips
For 8 + 7, model "make ten": 8 + 2 = 10, then 5 more makes 15.
Doubles and near doubles (6 + 6, then 6 + 7) are easier anchors than counting on.
Time a sheet only once accuracy is high. Speed drills on facts a child does not know yet build anxiety, not fluency.
How to use this worksheet maker
Press New worksheet for a fresh set of problems, then Print. To save a PDF instead, choose "Save as PDF" in the print window. Every sheet has a short code in the bottom corner. Copy the link to a sheet and you can print exactly the same problems again later, which is handy for retakes and for sharing with other teachers.
Common Core alignment: 1.OA.C.6, 2.OA.B.2 (Grades 1–2).