Partition to 100 | Worksheets - Primary Stars Education - Free Printable

The task in the image involves partitioning numbers to 100 using part-whole models. These are visual tools that show how a whole number can be split into two parts (addends). The goal is to fill in the missing numbers so that the sum of the two parts equals the whole number at the top.

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🔍 How to Solve:

Each diagram has:
- A whole number at the top.
- Two parts below it, one or both may be missing.
- You need to find the missing part such that:
Part + Part = Whole

So:
👉 Missing part = Whole − Given part

We’ll go through each question from the three sheets (labeled with stars: ★, ★★, ★★★) and solve them step by step.

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## ✔ Sheet 1: ★ (One Star)

a) 51 → 50 + ?

- 51 − 50 = 1
- Answer: 1

b) 22 → 20 + ?

- 22 − 20 = 2
- Answer: 2

c) 18 → ? + 8

- 18 − 8 = 10
- Answer: 10

d) 49 → ? + 9

- 49 − 9 = 40
- Answer: 40

e) 72 → 70 + ?

- 72 − 70 = 2
- Answer: 2

f) 45 → 40 + ?

- 45 − 40 = 5
- Answer: 5

g) 76 → ? + 6

- 76 − 6 = 70
- Answer: 70

h) 32 → ? + 2

- 32 − 2 = 30
- Answer: 30

i) 83 → 83 + ?

- This seems odd: 83 is already the whole, and one part is 83 → So other part must be 0
- But likely a typo? Wait — actually, this is showing 83 = 83 + 0, which is valid.
- Answer: 0

j) 91 → ? + 1

- 91 − 1 = 90
- Answer: 90

k) 26 → 20 + ?

- 26 − 20 = 6
- Answer: 6

l) 57 → 50 + ?

- 57 − 50 = 7
- Answer: 7

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## ✔ Sheet 2: ★★ (Two Stars)

a) 67 → 60 + ?

- 67 − 60 = 7
- Answer: 7

b) 43 → 40 + ?

- 43 − 40 = 3
- Answer: 3

c) 22 → ? + 2

- 22 − 2 = 20
- Answer: 20

d) 34 → ? + 4

- 34 − 4 = 30
- Answer: 30

e) 17 → 10 + ?

- 17 − 10 = 7
- Answer: 7

f) 87 → 80 + ?

- 87 − 80 = 7
- Answer: 7

g) 55 → ? + ?

- No part given → Can be any pair that adds to 55.
- Example: 50 + 5 (or 30 + 25, etc.)
- But since it's likely expecting tens and units: 50 + 5
- Answer: 50 and 5

h) 92 → ? + ?

- Again, no parts given → Possible: 90 + 2
- Answer: 90 and 2

i) 13 → ? + ?

- Example: 10 + 3
- Answer: 10 and 3

j) 45 → ? + ?

- Example: 40 + 5
- Answer: 40 and 5

k) 54 → ? + ?

- Example: 50 + 4
- Answer: 50 and 4

l) 71 → ? + ?

- Example: 70 + 1
- Answer: 70 and 1

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## ✔ Sheet 3: ★★★ (Three Stars)

These require more thinking — often partitioning into non-obvious pairs.

a) 73 → ? + ?

- Can be: 70 + 3, or 60 + 13, or 50 + 23, etc.
- Most common: 70 + 3
- Answer: 70 and 3

b) 96 → ? + ?

- Likely: 90 + 6
- Answer: 90 and 6

c) 61 → ? + ?

- Likely: 60 + 1
- Answer: 60 and 1

d) 32 → ? + ?

- Likely: 30 + 2
- Answer: 30 and 2

e) 18 → ? + ?

- Could be: 10 + 8, or 9 + 9, or 15 + 3
- Best for learning: 10 + 8
- Answer: 10 and 8

f) 57 → ? + ?

- Likely: 50 + 7
- Answer: 50 and 7

g) 49 → ? + ?

- Likely: 40 + 9
- Answer: 40 and 9

h) 51 → ? + ?

- Likely: 50 + 1
- Answer: 50 and 1

i) 66 → ? + ?

- Likely: 60 + 6
- Answer: 60 and 6

j) 81 → ? + ?

- Likely: 80 + 1
- Answer: 80 and 1

k) 29 → ? + ?

- Likely: 20 + 9
- Answer: 20 and 9

l) 15 → ? + ?

- Likely: 10 + 5
- Answer: 10 and 5

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📌 Summary of Answers:

#### Sheet 1 (★):
| Letter | Answer(s) |
|--------|------------------|
| a | 1 |
| b | 2 |
| c | 10 |
| d | 40 |
| e | 2 |
| f | 5 |
| g | 70 |
| h | 30 |
| i | 0 |
| j | 90 |
| k | 6 |
| l | 7 |

#### Sheet 2 (★★):
| Letter | Answer(s) |
|--------|-------------------|
| a | 7 |
| b | 3 |
| c | 20 |
| d | 30 |
| e | 7 |
| f | 7 |
| g | 50 and 5 |
| h | 90 and 2 |
| i | 10 and 3 |
| j | 40 and 5 |
| k | 50 and 4 |
| l | 70 and 1 |

#### Sheet 3 (★★★):
| Letter | Answer(s) |
|--------|-------------------|
| a | 70 and 3 |
| b | 90 and 6 |
| c | 60 and 1 |
| d | 30 and 2 |
| e | 10 and 8 |
| f | 50 and 7 |
| g | 40 and 9 |
| h | 50 and 1 |
| i | 60 and 6 |
| j | 80 and 1 |
| k | 20 and 9 |
| l | 10 and 5 |

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💡 Tips for Students:

- Use place value (tens and ones) when possible.
- Think: “What do I add to the known part to get the whole?”
- For blank partitions, try splitting into tens and ones first.

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