Grade 1/Base 10 Blocks
✏️ Decompose the Number: Tens and Ones
Students look at a two-digit number and break it into its tens and ones parts. For example, 34 becomes 3 tens + 4 ones. This worksheet builds number sense and connects written numbers to the place value system — a key foundation for addition, subtraction, and mental math.
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| # | Worksheet | Questions | Actions |
|---|---|---|---|
| Easy | |||
| 1 | 8 questions | ||
| 2 | 8 questions | ||
| 3 | 8 questions | ||
| 4 | 8 questions | ||
| 5 | 8 questions | ||
| 6 | 8 questions | ||
| 7 | 8 questions | ||
| 8 | Pro | 8 questions | |
| Medium | |||
| 1 | 8 questions | ||
| 2 | 8 questions | ||
| 3 | 8 questions | ||
| 4 | 8 questions | ||
| 5 | 8 questions | ||
| 6 | 8 questions | ||
| 7 | Pro | 8 questions | |
| Hard | |||
| 1 | 8 questions | ||
| 2 | 8 questions | ||
| 3 | 8 questions | ||
| 4 | 8 questions | ||
| 5 | 8 questions | ||
| 6 | 8 questions | ||
| 7 | Pro | 8 questions | |
What to Do Next
Practice Questions
- 13 = ? tens + ? ones
Show answer
1 ten + 3 ones
- 25 = ? tens + ? ones
Show answer
2 tens + 5 ones
- 30 = ? tens + ? ones
Show answer
3 tens + 0 ones
- 34 = ? tens + ? ones
Show answer
3 tens + 4 ones
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Teacher Resources
Teaching Notes
This worksheet is the reverse of Count the Blocks — instead of seeing blocks and writing a number, students see a number and identify its parts.
Common Mistakes
- Reversing the digits (writing 4 tens + 3 ones for the number 34)
- Thinking the tens place shows the total value (e.g., writing 34 tens instead of 3 tens)
- Struggling with round tens like 20 or 30 — remind them 0 ones is still valid
Differentiation
SupportGive students a place value chart to write the number in before filling in the blanks.
ChallengeAsk students to write the expanded form too: 34 = 30 + 4.
Discussion Questions
- What do the two digits in a two-digit number each mean?
- If a number has a 0 in the ones place, what does that tell you?
Extension Activities
- Write 5 two-digit numbers, then decompose each one
- Play partner quiz: one person says a number, the other writes the tens and ones
Learning Path
Skill Level
beginner
Estimated Time
12 minutes
Skills Practiced
Tens and ones decompose