Practice worksheet helping students visualize 2-digit subtraction and regrouping using base-10 block diagrams.

Let's solve each of the 2-digit subtraction problems using Base-10 Blocks and regrouping (also known as borrowing). The goal is to understand how to subtract numbers by breaking them into tens and ones, and when needed, regrouping a ten into ten ones.

We’ll go through each problem step-by-step:

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Problem 1: 85 - 28

Step 1: Represent 85 with Base-10 blocks:
- 8 tens (8 rods)
- 5 ones (5 small squares)

Step 2: Subtract 28:
- We need to remove 2 tens and 8 ones.
- But we only have 5 ones. So we need to regroup.

Regrouping:
- Take 1 ten from the 8 tens → now we have 7 tens.
- Break that ten into 10 ones → add to the 5 ones → now we have 15 ones.

Now we have:
- 7 tens
- 15 ones

Subtract:
- Remove 2 tens → 7 - 2 = 5 tens
- Remove 8 ones from 15 → 15 - 8 = 7 ones

Result: 5 tens + 7 ones = 57

✔ Answer: 57 (already filled in)

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Problem 2: 37 - 18

Step 1: Represent 37:
- 3 tens
- 7 ones

Step 2: Subtract 18 (1 ten and 8 ones)
- We can't take away 8 ones from 7 → need to regroup.

Regrouping:
- Take 1 ten from the 3 tens → now 2 tens
- Convert it to 10 ones → add to 7 ones → now 17 ones

Now:
- 2 tens
- 17 ones

Subtract:
- Remove 1 ten → 2 - 1 = 1 ten
- Remove 8 ones from 17 → 17 - 8 = 9 ones

Result: 1 ten + 9 ones = 19

✔ Answer: 19 (already filled in)

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Problem 3: 54 - 37

Step 1: Represent 54:
- 5 tens
- 4 ones

Step 2: Subtract 37 (3 tens and 7 ones)
- Can’t subtract 7 ones from 4 → regroup.

Regrouping:
- Take 1 ten from 5 tens → now 4 tens
- Convert to 10 ones → add to 4 → now 14 ones

Now:
- 4 tens
- 14 ones

Subtract:
- Remove 3 tens → 4 - 3 = 1 ten
- Remove 7 ones from 14 → 14 - 7 = 7 ones

Result: 1 ten + 7 ones = 17

✔ Answer: 17 (already filled in)

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Problem 4: 74 - 16

Step 1: Represent 74:
- 7 tens
- 4 ones

Step 2: Subtract 16 (1 ten and 6 ones)
- Can’t subtract 6 ones from 4 → regroup.

Regrouping:
- Take 1 ten → now 6 tens
- Convert to 10 ones → add to 4 → now 14 ones

Now:
- 6 tens
- 14 ones

Subtract:
- Remove 1 ten → 6 - 1 = 5 tens
- Remove 6 ones from 14 → 14 - 6 = 8 ones

Result: 5 tens + 8 ones = 58

✔ Answer: 58 (already filled in)

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Problem 5: 93 - 27

Step 1: Represent 93:
- 9 tens
- 3 ones

Step 2: Subtract 27 (2 tens and 7 ones)
- Can’t subtract 7 ones from 3 → regroup.

Regrouping:
- Take 1 ten → now 8 tens
- Convert to 10 ones → add to 3 → now 13 ones

Now:
- 8 tens
- 13 ones

Subtract:
- Remove 2 tens → 8 - 2 = 6 tens
- Remove 7 ones from 13 → 13 - 7 = 6 ones

Result: 6 tens + 6 ones = 66

✔ Answer: 66 (already filled in)

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Problem 6: 64 - 39

Step 1: Represent 64:
- 6 tens
- 4 ones

Step 2: Subtract 39 (3 tens and 9 ones)
- Can’t subtract 9 ones from 4 → regroup.

Regrouping:
- Take 1 ten → now 5 tens
- Convert to 10 ones → add to 4 → now 14 ones

Now:
- 5 tens
- 14 ones

Subtract:
- Remove 3 tens → 5 - 3 = 2 tens
- Remove 9 ones from 14 → 14 - 9 = 5 ones

Result: 2 tens + 5 ones = 25

✔ Answer: 25 (already filled in)

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✔ Final Answers:

1. 85 - 28 = 57
2. 37 - 18 = 19
3. 54 - 37 = 17
4. 74 - 16 = 58
5. 93 - 27 = 66
6. 64 - 39 = 25

All answers are correct and match the filled-in values.

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🔍 Summary of Key Concept:

When subtracting 2-digit numbers using base-10 blocks:
- Use tens rods and ones cubes.
- If you don’t have enough ones to subtract, regroup one ten into ten ones.
- Then subtract the tens and ones separately.

This method builds strong number sense and understanding of place value!

Let me know if you'd like a visual representation or printable version!