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Subtraction Facts within 20FREEWorksheet Generator(Grade 1)

Subtraction Facts within 20 worksheets (Grade 1) with step-by-step answer keys. Generate unlimited unique practice sheets with fresh problems.

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Set A • 10 Qs

PanMaths.comSubtraction Facts within 20 Worksheets • Set A (Medium)

Name: __________________________

Date: _____________ Period: ____

Score: _____ / 10

1.20−3

= ______

Workspace:

2.8−6

= ______

Workspace:

3.3−2

= ______

Workspace:

4.4−3

= ______

Workspace:

5.2−1

= ______

Workspace:

6.17−10

= ______

Workspace:

7.16−8

= ______

Workspace:

8.15−7

= ______

Workspace:

9.6−4

= ______

Workspace:

10.4−1

= ______

Workspace:

PanMaths.com • Free Math Worksheet Generator • Set A (Medium)Page 1 of 2

PanMaths.comAnswer Key & Worked Solutions • Set A (Medium)

Answer Key

Total Problems: 10

1.20−3

= 17

1. Core Subtraction Fact: 20 − 3 = 17

2. Inverse Addition Proof: 17 + 3 = 20 ✅

2.8−6

= 2

1. Core Subtraction Fact: 8 − 6 = 2

2. Inverse Addition Proof: 2 + 6 = 8 ✅

3.3−2

= 1

1. Core Subtraction Fact: 3 − 2 = 1

2. Inverse Addition Proof: 1 + 2 = 3 ✅

4.4−3

= 1

1. Core Subtraction Fact: 4 − 3 = 1

2. Inverse Addition Proof: 1 + 3 = 4 ✅

5.2−1

= 1

1. Core Subtraction Fact: 2 − 1 = 1

2. Inverse Addition Proof: 1 + 1 = 2 ✅

6.17−10

= 7

1. Core Subtraction Fact: 17 − 10 = 7

2. Inverse Addition Proof: 7 + 10 = 17 ✅

7.16−8

= 8

1. Core Subtraction Fact: 16 − 8 = 8

2. Inverse Addition Proof: 8 + 8 = 16 ✅

8.15−7

= 8

1. Core Subtraction Fact: 15 − 7 = 8

2. Inverse Addition Proof: 8 + 7 = 15 ✅

9.6−4

= 2

1. Core Subtraction Fact: 6 − 4 = 2

2. Inverse Addition Proof: 2 + 4 = 6 ✅

10.4−1

= 3

1. Core Subtraction Fact: 4 − 1 = 3

2. Inverse Addition Proof: 3 + 1 = 4 ✅

PanMaths.com • Answer Key & Worked SolutionsPage 2 of 2

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Worksheet Info

Categorygrade-1

Grade LevelGrade 1

DifficultyEasy, Medium, Hard, Sprint

Time5-10 min

CCSS CodeCCSS.MATH.CONTENT.1.OA.C.6

Skills Practiced

✓ Subtraction Facts within 20

Key Strategies

🔟 Get to 10 First (Back Down Through 10): For 15 − 7: Split 7 into 5 and 2. Subtract 15 − 5 = 10, then subtract 10 − 2 = 8!
🔄 Use Related Addition Facts: If you know 9 + 6 = 15, you instantly know 15 − 6 = 9 and 15 − 9 = 6.
🤝 Half of Doubles Facts: Remember your doubles: 16 − 8 = 8, 14 − 7 = 7, 12 − 6 = 6.

🎮 Interactive Warm-Up

Subtraction Meteor Defense Arcade

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Related Worksheets

📄 Number Line Hops (Within 20)View →📄 Number Bonds to 10View →📄 Number Bonds to 20View →📄 Addition Facts within 10View →📄 Addition Facts within 20View →📄 Making 10 Addition StrategyView →

📜 Standard: CCSS.MATH.CONTENT.1.OA.C.6🔗 CCSS.MATH.CONTENT.1.OA.B.4🔗 CCSS.MATH.CONTENT.1.OA.A.1

Mastering Subtraction Facts within 20: Core Concepts & Mental Models

Subtracting from teen numbers (11 to 20) introduces the crucial mental math strategy of 'Decomposing to Ten'. For 14 − 6, first subtract 4 to reach 10, then subtract the remaining 2 to reach 8. This eliminates the need for fingers and lays the groundwork for multi-digit column borrowing.

Worked Example & SolutionTeacher Step-by-Step Method

📝 Problem: Solve: 13 − 5 = ?

Worked Solution: 1. Back down through 10: 13 − 3 = 10. 2. Remaining to subtract: 5 − 3 = 2. 3. 10 − 2 = 8. (Proof: 8 + 5 = 13 ✅).

💡 Essential Strategies for Subtraction Facts within 20

🔟 Get to 10 First (Back Down Through 10)

For 15 − 7: Split 7 into 5 and 2. Subtract 15 − 5 = 10, then subtract 10 − 2 = 8!

🔄 Use Related Addition Facts

If you know 9 + 6 = 15, you instantly know 15 − 6 = 9 and 15 − 9 = 6.

🤝 Half of Doubles Facts

Remember your doubles: 16 − 8 = 8, 14 − 7 = 7, 12 − 6 = 6.

⚠️ Common Mistakes & Teacher Fixes

⚠️Stopping at 10 and forgetting the second step

Why students stumble: For 14 − 6, student subtracts 4 to reach 10 and writes 10 as the answer.

Teacher Fix: Always check: 'You only subtracted 4, but you needed to subtract 6! Subtract 2 more from 10.'

Example: 14 − 6 = 8, not 10.

📖 Key Mathematical Vocabulary

Teen Number

A number from 11 to 19 made of one group of ten and some extra ones.

Decompose Leading to 10

Splitting the subtrahend into two parts to reach 10 as an intermediate landmark.

❓ Frequently Asked Questions

How do you solve a subtraction facts within 20 problem step by step?

Here is a worked example: "Solve: 13 − 5 = ?". Solution: 1. Back down through 10: 13 − 3 = 10. 2. Remaining to subtract: 5 − 3 = 2. 3. 10 − 2 = 8. (Proof: 8 + 5 = 13 ✅).

What is the core learning objective for subtraction facts within 20?

Subtract within 20, demonstrating fluency for subtraction within 10 and using strategies such as decomposing a number leading to a ten. This directly aligns with Common Core Standard CCSS.MATH.CONTENT.1.OA.C.6.

What is the most common mistake students make with subtraction facts within 20?

A frequent pitfall is: "Stopping at 10 and forgetting the second step". Why students stumble: For 14 − 6, student subtracts 4 to reach 10 and writes 10 as the answer. How to fix it: Always check: 'You only subtracted 4, but you needed to subtract 6! Subtract 2 more from 10.' (Example: 14 − 6 = 8, not 10.)

How does the unlimited subtraction facts within 20 worksheet generator work?

Every click of 'Generate New Worksheet' creates a completely fresh set of subtraction facts within 20 problems with unique numbers. No two worksheets are ever the same — perfect for daily practice, homework variety, and preventing student copying. You can also customize the problem count (6, 8, 10, 12, 15, or 20 problems per sheet).

Are these subtraction facts within 20 worksheets free to print with answer keys?

Yes! Every single worksheet on PanMaths is 100% free with no sign-up needed. Each sheet includes a dedicated Answer Key on Page 2 with step-by-step intermediate evaluation lines for 1-minute grading.