Estimating Sum and Difference worksheet from SplashLearn, designed to help students practice rounding numbers and calculating estimated sums and differences.

Let's solve the problem step by step. The task is to estimate the sum or difference by rounding off the numbers to the nearest hundred (or thousand, depending on the size of the numbers), then performing the operation.

We'll go through each problem one by one.

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🔹 Estimate the Sum

We round each number to the nearest hundred (unless the numbers are very large, we may round to the nearest thousand for simplicity and estimation).

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1. 3,854 + 6,028

- Round 3,854 → 3,900 (nearest hundred)
- Round 6,028 → 6,000 (nearest hundred)
- Estimated sum:
$ 3,900 + 6,000 = \boxed{9,900} $

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2. 8,322 + 1,103

- Round 8,322 → 8,300
- Round 1,103 → 1,100
- Estimated sum:
$ 8,300 + 1,100 = \boxed{9,400} $

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3. 67,551 + 85,302

- Round 67,551 → 67,600 (nearest hundred)
- Round 85,302 → 85,300
- Estimated sum:
$ 67,600 + 85,300 = \boxed{152,900} $

> Alternatively, you might round to nearest thousand:
> - 67,551 → 68,000
> - 85,302 → 85,000
> - Sum: 68,000 + 85,000 = 153,000
> But since the question says "round off", and the numbers are in hundreds, rounding to nearest hundred is more precise for estimation.

But let’s check:
67,551 → 67,600 (correct)
85,302 → 85,300 (correct)
Sum: 67,600 + 85,300 = 152,900

✔ So:
→ 67,600 + 85,300 = 152,900

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4. 10,364 + 59,493

- 10,364 → 10,400
- 59,493 → 59,500
- Sum:
$ 10,400 + 59,500 = \boxed{69,900} $

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5. 94,650 + 2,113

- 94,650 → 94,700
- 2,113 → 2,100
- Sum:
$ 94,700 + 2,100 = \boxed{96,800} $

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🔹 Estimate the Difference

Now subtract after rounding to nearest hundred.

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6. 9,493 – 2,324

- 9,493 → 9,500
- 2,324 → 2,300
- Difference:
$ 9,500 - 2,300 = \boxed{7,200} $

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7. 5,036 – 1,945

- 5,036 → 5,000
- 1,945 → 1,900
- Difference:
$ 5,000 - 1,900 = \boxed{3,100} $

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8. 68,931 – 11,585

- 68,931 → 68,900
- 11,585 → 11,600
- Difference:
$ 68,900 - 11,600 = \boxed{57,300} $

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9. 74,832 – 15,002

- 74,832 → 74,800
- 15,002 → 15,000
- Difference:
$ 74,800 - 15,000 = \boxed{59,800} $

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10. 35,846 – 5,394

- 35,846 → 35,800
- 5,394 → 5,400
- Difference:
$ 35,800 - 5,400 = \boxed{30,400} $

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✔ Final Answers:

#### Estimate the sum:

1. 3,854 + 6,028 → 3,900 + 6,000 = 9,900
2. 8,322 + 1,103 → 8,300 + 1,100 = 9,400
3. 67,551 + 85,302 → 67,600 + 85,300 = 152,900
4. 10,364 + 59,493 → 10,400 + 59,500 = 69,900
5. 94,650 + 2,113 → 94,700 + 2,100 = 96,800

#### Estimate the difference:

6. 9,493 – 2,324 → 9,500 – 2,300 = 7,200
7. 5,036 – 1,945 → 5,000 – 1,900 = 3,100
8. 68,931 – 11,585 → 68,900 – 11,600 = 57,300
9. 74,832 – 15,002 → 74,800 – 15,000 = 59,800
10. 35,846 – 5,394 → 35,800 – 5,400 = 30,400

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📝 Explanation:

- Rounding Rule: We rounded to the nearest hundred, because the numbers are mostly in the thousands or tens of thousands.
- For example:
- 3,854 → Look at tens digit (5), so round up: 3,900
- 6,028 → Tens digit is 2 < 5 → round down to 6,000
- Estimation helps us get a quick, approximate answer without exact calculation.

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