Subtraction Word Problems Within 20- Practice Guide
What Are Subtraction Word Problems Within 20?
Subtraction word problems within 20 are math questions that describe a real-world situation using words, then ask you to find the difference between two numbers—no larger than 20.
Example: "Sarah had 14 apples. She gave 6 to her friend. How many apples does Sarah have left?"
That's it. The numbers stay small, but the thinking required is real.
Why These Problems Matter
Kids who master subtraction within 20 build a foundation for everything that comes next:
- Multi-digit subtraction
- Problem-solving skills
- Reading comprehension in math contexts
- Mental math speed
These aren't just "beginner problems." They're the checkpoint before math gets complicated. If a child struggles here, they'll struggle everywhere else.
Types of Subtraction Word Problems
Not all word problems are structured the same way. Here are the main types kids encounter:
1. Take Away / Result Unknown
The classic "something happened" problem. You start with a number, something is removed, you find what's left.
"Tom had 17 stickers. He lost 9. How many does he have now?"
2. Compare / Difference Unknown
Two groups exist. You figure out how much bigger one is than the other.
"Emma has 12 crayons. Jake has 8. How many more crayons does Emma have?"
3. Add To / Change Unknown
You know the start and the end, but not what changed.
"Mia had some candies. She ate 5 and had 11 left. How many did she start with?"
4. Start Unknown
Similar structure, different wording. The starting number is missing.
"There were some birds on a wire. 7 flew away. 13 were left. How many birds were on the wire?"
How to Solve Subtraction Word Problems Within 20
Follow this step-by-step process every time:
Step 1: Read the Whole Problem
Don't try to solve while reading. Just read. Get the story straight first.
Step 2: Find the Key Numbers
Look for what you're starting with and what's being taken away or compared. Circle or underline them.
Step 3: Identify the Question
What are you actually solving for? "Left," "more," "fewer," "difference"—all point to subtraction.
Step 4: Write the Number Sentence
Translate the words into math. Use the structure: Starting Number − What Was Taken Away = What's Left
Step 5: Solve
Count back, use number bonds, or recall facts. Whatever works. The method matters less than getting the right answer.
Step 6: Check Your Work
Add the answer back to what was subtracted. Does it match your starting number? If yes, you're good.
Common Mistakes to Watch For
- Reading too fast: Skipping words changes the problem entirely
- Adding instead of subtracting: "More" doesn't always mean add
- Ignoring the question: Solving for the wrong thing is common when kids rush
- Misreading numbers: 13 vs. 31, or 12 vs. 15
These mistakes are fixable. The fix is slow reading and double-checking—not more worksheets.
Practice Strategies That Actually Work
Flashcards don't cut it for word problems. You need a different approach.
Use Physical Objects
Pencils, blocks, coins—anything you can count and move. Kids who manipulate objects understand subtraction better than kids who just memorize.
Draw the Problem
A quick sketch beats a blank stare. Circles for items, X marks for what's gone. It works.
Act It Out
Stand up, grab 15 objects, give 6 to someone else, sit down. Physical movement creates memory.
Read Aloud
Reading the problem out loud forces kids to process every word. Silent reading lets them skim.
Mix Addition and Subtraction
Don't isolate subtraction. If kids only practice one operation, they forget the other. Mix problems together.
Subtraction Methods Comparison
| Method | Best For | Speed | Works Well With |
|---|---|---|---|
| Counting Back | Small differences (1-5) | Slow | Visual learners |
| Number Bonds | Numbers that make 10 | Medium | Kids who know pairs to 10 |
| Mental Decomposition | Any subtraction within 20 | Fast | Students with strong number sense |
| Objects / Manipulatives | Beginners, visual learners | Slow | Concrete thinkers |
| Drawings | Word problems specifically | Medium | Kids who struggle with abstraction |
Sample Problems to Practice
Work through these with your child or students:
- "Jake had 16 baseball cards. He gave 7 to his brother. How many does he have left?" (Answer: 9)
- "Lisa has 11 markers. Amy has 15 markers. How many more markers does Amy have?" (Answer: 4)
- "There were 18 cookies on a plate. Mom ate 9. How many cookies are left?" (Answer: 9)
- "A farmer had 20 chickens. 6 got out of the pen. How many chickens are still inside?" (Answer: 14)
- "Ben had some balloons. 8 popped. He has 12 left. How many balloons did he start with?" (Answer: 20)
When to Move Beyond 20
Ready to push forward? Move on when a child can:
- Solve subtraction word problems within 20 independently
- Explain their thinking, not just give the answer
- Check their own work and find mistakes
- Handle mixed addition and subtraction problems without confusion
If those aren't solid yet, stay here. Rushing ahead creates gaps that take months to fix.
Bottom Line
Subtraction word problems within 20 aren't complicated to understand, but they require precision. Read carefully. Identify what changes. Solve. Check your work. That's the whole process.
Don't overcomplicate it with fancy methods or elaborate systems. The kids who get it are the ones who read the problem twice and think before they calculate.