1st Grade Subtraction Within 20 Worksheet Solutions (PDF)
This subtraction within 20 answers for 1st Grade covers subtraction within 20 (Common Core 1.OA.A.1, 1.OA.B.4, 1.OA.C.6), with a free PDF to print.
Here are the full answers for the subtraction within 20 worksheet. Each answer shows a strategy: counting back, thinking addition, or using a fact family. Check the difference by adding it back.
Grade 1 · Common Core State Standards: 1.OA.A.1, 1.OA.B.4, 1.OA.C.6
Subtraction within 20 answers: exercises 1 to 10
Exercise 1 – Cross out counters
8 counters, 3 crossed out. \(8 – 3 = 5\).
There are 5 left.
Exercise 2 – Take away
Count back 2 from 9: 8, 7. \(9 – 2 = 7\).
The difference is 7.
Exercise 3 – Count back 3
12, then 11, 10, 9. \(12 – 3 = 9\).
You reach 9.
Exercise 4 – Subtract zero
Nothing is taken away. \(8 – 0 = 8\).
The difference is 8.
Exercise 5 – Take all away
All 6 are taken away. \(6 – 6 = 0\).
The difference is 0.
Exercise 6 – Think addition
\(4 + 5 = 9\), so the missing number is 5. \(9 – 4 = 5\).
The missing number is 5 and the difference is 5.
Exercise 7 – Subtract from 14
4 ones come off 14 and leave 10. \(14 – 4 = 10\).
The difference is 10.
Exercise 8 – Subtract through ten
Take away 3 to reach 10. Then take away 2 more. \(13 – 3 = 10\), \(10 – 2 = 8\). \(13 – 5 = 8\).
The difference is 8.
Exercise 9 – Subtract 15 – 8
Think: \(8 + 7 = 15\). So \(15 – 8 = 7\).
The difference is 7.
Exercise 10 – Fact family
\(5 + 7 = 12\), \(7 + 5 = 12\), \(12 – 5 = 7\), \(12 – 7 = 5\).
The four facts use 5, 7 and 12.
Exercises 11 and up
Exercise 11 – Missing addend
Think \(14 – 6\). \(14 – 6 = 8\). Check: \(6 + 8 = 14\).
The missing number is 8.
Exercise 12 – Subtract 17 – 9
Count up from 9 to 10 is 1, then 10 to 17 is 7. 1 + 7 = 8. \(17 – 9 = 8\).
The difference is 8.
Exercise 13 – Missing part
\(16 – 9 = 7\). Check: \(9 + 7 = 16\).
The missing part is 7.
Exercise 14 – Which is more?
\(12 – 7 = 5\).
There are 5 more blue counters.
Exercise 15 – Fact family gap
\(16 – 9 = 7\). The missing number is 7 because \(9 + 7 = 16\).
The third number is 7.
Exercise 16 – Stickers given away
\(18 – 9 = 9\).
Priya has 9 stickers left.
Exercise 17 – Shell comparison
\(15 – 8 = 7\).
Sofia found 7 more shells.
Exercise 18 – Crayon parts
Whole 13, one part 6. \(13 – 6 = 7\). Check: \(6 + 7 = 13\).
There are 7 crayons on the table.
Exercise 19 – How many more?
\(9 + \text{?} = 17\). \(17 – 9 = 8\).
Jamal needs 8 more cards.
Exercise 20 – Find the odd one out
\(8 + 6 = 14\) uses 6, 8, 14. \(14 – 6 = 8\) uses 6, 8, 14. \(8 + 14 = 22\) uses 22.
Sentence C does not belong.
Key facts behind this subtraction within 20 answers
- The difference is the answer to a subtraction problem.
- Counting back: hop back from the whole, one number at a time.
- Think addition: 13 – 5 asks what to add to 5 to get 13.
- A fact family uses three numbers, like 8, 7 and 15.
- Subtracting 0 or the whole number gives easy answers: 6 – 0 = 6 and 6 – 6 = 0.
How to use this subtraction within 20 answers
Cover each solution, solve the exercise again, then uncover it and compare every line. If your answer differs, find the first step that changed and redo the exercise from there.
All Grade 1 chapters: Grade 1 math.
Print this page
Download PDFDownload the 1st Grade Subtraction Within 20 Worksheet Solutions (PDF, 73 KB)More 1st Grade math
Lessons
See all
Worksheets
See all
Tests
See all
Telling Time to the Hour and Half Hour Test with Point Values- 2D and 3D Shapes Test with Point Values
- The Equal Sign and Word Problems Test with Point Values
- Adding and Subtracting Tens Within 100 Test with Point Values
- Subtraction Within 20 Test with Point Values
- Counting and Numbers to 20 Test with Point Values
