Worksheets on Composing and Decomposing Numbers in Grade 1

Master composing and decomposing numbers through comprehensive worksheets: place value, tens and ones, number bonds activities designed for young learners.

Worksheet Concepts and Structure
🔢 Composing & Decomposing Worksheets 🔢
10
Tens
1
Ones
15
1T + 5O
Key Definitions:

Composing: Putting numbers together to make a larger number

Decomposing: Breaking apart a number into smaller parts

Place Value: Where a digit sits tells its value (tens, ones)

Base Ten: Our number system uses groups of 10

Number Bonds: Different ways to make the same number

Worksheets: Structured practice sheets for skill development

Number = Tens + Ones
Place Value Formula
Worksheet Strategy:
  1. Read the instructions: Understand what to do
  2. Look at the number: Identify the total or parts
  3. Find tens and ones: Use visual aids if needed
  4. Fill in the blanks: Write answers clearly
  5. Check your work: Verify answers make sense
Tip 1: Count by tens first (10, 20, 30...)
Tip 2: Use your fingers to group by 10!
Tip 3: Draw circles in groups of 10.
Important: Every number can be broken into tens and ones.
Remember: 10 ones = 1 ten.
Worksheets: Pages 1-3
1 Basic Composing
Worksheet 1: Basic Composing
Build numbers using tens and ones:
2 tens + 3 ones = ___
1 ten + 7 ones = ___
3 tens + 5 ones = ___
Worksheet Objective:

Composing: Building numbers from their place value parts

How to Complete:
  1. Count the tens (2 tens = 20)
  2. Count the ones (3 ones = 3)
  3. Add them together (20 + 3 = 23)
  4. Write the answer (23)
10
10
1
1
1
2 tens + 3 ones =
1 ten + 7 ones =
3 tens + 5 ones =
Step 1: Count the tens

2 tens = 2 × 10 = 20

Step 2: Count the ones

3 ones = 3 × 1 = 3

Step 3: Add them together

20 + 3 = 23

Step 4: Check your work

Does 2 tens + 3 ones = 23? Yes!

2 tens + 3 ones = 23
Worksheet Answers:

2 tens + 3 ones = 23, 1 ten + 7 ones = 17, 3 tens + 5 ones = 35

Worksheet Rules:

• Place value: Tens and ones positions matter

• Counting: Group by tens first

• Verification: Check your answer makes sense

2 Basic Decomposing
Worksheet 2: Basic Decomposing
Break apart numbers into tens and ones:
27 = ___ tens + ___ ones
45 = ___ tens + ___ ones
19 = ___ tens + ___ ones
Worksheet Objective:

Decomposing: Breaking numbers into their place value parts

10
10
1
1
1
1
1
1
1
27 = tens + ones
45 = tens + ones
19 = tens + ones
Step 1: Look at the number

We have the number 27

Step 2: Count the tens

How many tens are in 27? 2 tens (20)

Step 3: Count the ones

After taking away 20, we have 7 left

Step 4: Write the decomposition

27 = 20 + 7 = 2 tens + 7 ones

27 = 2 tens + 7 ones
Worksheet Answers:

27 = 2 tens + 7 ones, 45 = 4 tens + 5 ones, 19 = 1 ten + 9 ones

Worksheet Rules:

• Subtraction: Take away groups of 10 first

• Place value: Tens and ones positions

• Verification: Check 20 + 7 = 27

3 Number Bonds
Worksheet 3: Number Bonds
Show different ways to make each number:
Ways to make 12: __ + __, __ + __, __ + __
Ways to make 15: __ + __, __ + __, __ + __
Ways to make 18: __ + __, __ + __, __ + __
Worksheet Objective:

Number Bonds: Showing different ways to compose the same number

Ways to make 12:
Ways to make 15:
Ways to make 18:
Step 1: Start with place value

12 = 10 + 2 (1 ten + 2 ones)

Step 2: Find other combinations

12 = 9 + 3, 8 + 4, 7 + 5, etc.

Step 3: Check each combination

9 + 3 = 12, 8 + 4 = 12 ✓

Step 4: Practice more

Try to find as many as possible!

12 = 10+2, 9+3, 8+4, 15 = 10+5, 9+6, 8+7...
Worksheet Answers:

Multiple ways to make each number using addition

Worksheet Rules:

• Flexibility: Numbers can be made multiple ways

• Addition: Combine parts to make whole

• Verification: Check each combination equals target

Worksheets: Pages 4-5
4 Mixed Practice
Worksheet 4: Mixed Practice
Complete these problems:
34 = ___ tens + ___ ones
2 tens + 8 ones = ___
56 = ___ tens + ___ ones
4 tens + 3 ones = ___
Worksheet Objective:

Mixed Practice: Alternating between composing and decomposing

Problem 1: 34 = ___ tens + ___ ones

34 has 3 tens (30) and 4 ones (4)

Problem 2: 2 tens + 8 ones = ___

2 tens = 20, 8 ones = 8, so 20 + 8 = 28

Problem 3: 56 = ___ tens + ___ ones

56 has 5 tens (50) and 6 ones (6)

Problem 4: 4 tens + 3 ones = ___

4 tens = 40, 3 ones = 3, so 40 + 3 = 43

34 = tens + ones
2 tens + 8 ones =
56 = tens + ones
4 tens + 3 ones =
Step 1: Solve first problem

34 = 3 tens + 4 ones

Step 2: Solve second problem

2 tens + 8 ones = 28

Step 3: Solve third problem

56 = 5 tens + 6 ones

Step 4: Solve fourth problem

4 tens + 3 ones = 43

Step 5: Verify all answers

30+4=34, 20+8=28, 50+6=56, 40+3=43 ✓

34=3T+4O, 28, 56=5T+6O, 43
Worksheet Results:

34=3T+4O, 2 tens+8 ones=28, 56=5T+6O, 4 tens+3 ones=43

Worksheet Rules:

• Alternating: Switch between composing and decomposing

• Verification: Check each answer

• Consistency: Apply same methods to all problems

5 Challenge Problems
Worksheet 5: Challenge Problems
Word problems:
Emma has 3 tens and 6 ones. How many does she have total?
Tom has 42 marbles. How many tens and ones does he have?
What number has 5 tens and 9 ones?
If I have 6 tens and need 67 total, how many more ones do I need?
Worksheet Objective:

Application: Using composing and decomposing in real contexts

Emma's Problem: 3 tens + 6 ones = ?

3 tens = 30, 6 ones = 6, so 30 + 6 = 36

Tom's Problem: 42 = ? tens + ? ones

42 has 4 tens (40) and 2 ones (2)

Third Problem: 5 tens + 9 ones = ?

5 tens = 50, 9 ones = 9, so 50 + 9 = 59

Fourth Problem: 6 tens + ? ones = 67

6 tens = 60, so 67 - 60 = 7 more ones needed

Emma:
Tom: tens + ones
Third:
Fourth: more ones
Step 1: Solve Emma's problem

3 tens + 6 ones = 36 total

Step 2: Solve Tom's problem

42 = 4 tens + 2 ones

Step 3: Solve third problem

5 tens + 9 ones = 59

Step 4: Solve fourth problem

6 tens = 60, so 67 - 60 = 7 more ones needed

Step 5: Check all solutions

All answers verified and correct!

Emma: 36, Tom: 4T+2O, Third: 59, Fourth: 7 more
Challenge Results:

Emma has 36, Tom has 4 tens + 2 ones, answer is 59, need 7 more ones

Worksheet Rules:

• Word problems: Identify key information

• Application: Use place value in real contexts

• Verification: Check solutions make sense

Composing and Decomposing Numbers Worksheets: Complete Guide

What Are These Worksheets?

These worksheets provide structured practice for understanding how numbers are built and broken down using place value. Each worksheet focuses on a specific skill:

  • Composing: Building numbers from tens and ones
  • Decomposing: Breaking numbers into tens and ones
  • Number Bonds: Different ways to make the same number
  • Application: Using concepts in real-world problems
  • Mixed Practice: Alternating between composing and decomposing

Why Use These Worksheets?

Worksheets offer focused practice and help children:

  • Develop number sense and fluency
  • Build confidence with larger numbers
  • Prepare for addition and subtraction
  • Reinforce concepts through repetition
  • Provide assessment opportunities

Worksheet Types

Fill-in-the-blank: Complete missing tens or ones
Matching: Connect numbers to their parts
Word Problems: Apply concepts in context
Mixed Review: Comprehensive skill assessment

How to Approach Each Worksheet

Read Carefully: Understand what each question asks

Use Visual Aids: Draw tens and ones if needed

Work Systematically: Complete questions in order

Check Your Work: Verify answers make sense

Progressive Difficulty

  • Worksheet 1: Numbers 11-19 (teen numbers)
  • Worksheet 2: Numbers 20-39
  • Worksheet 3: Numbers 40-69
  • Worksheet 4: Numbers 70-99
  • Worksheet 5: Mixed problems and word problems

Success Strategies

  • Count by tens first, then add ones
  • Use drawings to visualize groups
  • Check answers by recomposing
  • Practice regularly for fluency

Key Learning Objectives

  • Recognize that two-digit numbers are composed of tens and ones
  • Fluently decompose numbers into tens and ones
  • Compose numbers from given tens and ones
  • Understand the relationship between tens and ones
  • Apply concepts to solve word problems
  • Build foundation for future math concepts

Assessment Indicators

  • Accurately identifies tens and ones in numbers
  • Composes numbers from given parts
  • Decomposes numbers correctly
  • Applies concepts to word problems
  • Demonstrates understanding through explanation
  • Shows flexibility in number representation

Questions & Answers

Question: Why do we need to learn about tens and ones? Can't I just count regular numbers?

Answer: Great question! Learning about tens and ones helps your brain understand how numbers work, just like learning the alphabet helps you read words!

  • It makes adding and subtracting much easier: 23 + 15 becomes (20 + 10) + (3 + 5) = 38
  • It helps you understand bigger numbers later
  • It makes mental math faster and more accurate
  • It's the foundation for all future math

Think of it like organizing your toys - it's easier to count and find what you need when things are grouped together!

Question: My child is struggling with the concept of tens and ones. How can I help at home?

Answer: Here are effective home strategies:

  • Use everyday objects: bundle 10 straws together, group 10 coins
  • Practice with real numbers: count items in groups of 10
  • Play games: number card matching, place value bingo
  • Use visual aids: draw tens and ones, use base ten blocks
  • Be patient and encourage: celebrate small successes

The key is making it hands-on and fun! Regular practice with concrete materials helps build understanding.

Question: What are some effective activities for reinforcing composing and decomposing skills?

Answer: Here are proven activities:

  • Base ten block buildings: Construct numbers with physical blocks
  • Number bond flowers: Petals add up to center number
  • Place value mats: Organize tens and ones systematically
  • Counting collections: Group items by tens
  • Interactive games: Digital or physical matching games

Variety helps maintain engagement while reinforcing the core concepts!