Estimating Sums Worksheets - 15 Worksheets Library - Free Printable

Of course! Let’s solve the worksheet step by step.

The task is to estimate addition by rounding numbers to the nearest hundred (top section) and then to the nearest thousand (bottom section).

---

## 🔹 SECTION 1: Estimate by rounding to the nearest hundred

✔ How to round to the nearest hundred:

- Look at the tens digit.
- If it’s 5 or more, round up.
- If it’s 4 or less, round down.
- Replace the tens and ones digits with zeros.

---

📌 Problem Set 1:

1. 324 + 454
- 324 → tens digit is 2 → round down → 300
- 454 → tens digit is 5 → round up → 500
- Estimate: 300 + 500 = 800

2. 965 + 457
- 965 → tens digit is 6 → round up → 1000
- 457 → tens digit is 5 → round up → 500
- Estimate: 1000 + 500 = 1500

3. 325 + 247
- 325 → tens digit is 2 → round down → 300
- 247 → tens digit is 4 → round down → 200
- Estimate: 300 + 200 = 500

---

📌 Problem Set 2:

4. 365 + 124
- 365 → tens digit is 6 → round up → 400
- 124 → tens digit is 2 → round down → 100
- Estimate: 400 + 100 = 500

5. 365 + 247
- 365 → 400
- 247 → 200
- Estimate: 400 + 200 = 600

6. 987 + 214
- 987 → tens digit is 8 → round up → 1000
- 214 → tens digit is 1 → round down → 200
- Estimate: 1000 + 200 = 1200

---

📌 Problem Set 3:

7. 632 + 247
- 632 → tens digit is 3 → round down → 600
- 247 → 200
- Estimate: 600 + 200 = 800

8. 987 + 247
- 987 → 1000
- 247 → 200
- Estimate: 1000 + 200 = 1200

9. 365 + 247
- Already did this above → 400 + 200 = 600

---

✔ Answers for Section 1 (Nearest Hundred):

| Problem | Rounded Numbers | Estimated Sum |
|---------------|---------------------|---------------|
| 324 + 454 | 300 + 500 | 800 |
| 965 + 457 | 1000 + 500 | 1500 |
| 325 + 247 | 300 + 200 | 500 |
| 365 + 124 | 400 + 100 | 500 |
| 365 + 247 | 400 + 200 | 600 |
| 987 + 214 | 1000 + 200 | 1200 |
| 632 + 247 | 600 + 200 | 800 |
| 987 + 247 | 1000 + 200 | 1200 |
| 365 + 247 | 400 + 200 | 600 |

---

## 🔹 SECTION 2: Estimate by rounding to the nearest thousand

✔ How to round to the nearest thousand:

- Look at the hundreds digit.
- If it’s 5 or more, round up.
- If it’s 4 or less, round down.
- Replace the hundreds, tens, and ones digits with zeros.

---

📌 Problem Set 1:

1. 2547 + 3214
- 2547 → hundreds digit is 5 → round up → 3000
- 3214 → hundreds digit is 2 → round down → 3000
- Estimate: 3000 + 3000 = 6000

2. 3214 + 1247
- 3214 → 3000
- 1247 → hundreds digit is 2 → round down → 1000
- Estimate: 3000 + 1000 = 4000

3. 3698 + 2471
- 3698 → hundreds digit is 6 → round up → 4000
- 2471 → hundreds digit is 4 → round down → 2000
- Estimate: 4000 + 2000 = 6000

---

📌 Problem Set 2:

4. 3254 + 2478
- 3254 → hundreds digit is 2 → round down → 3000
- 2478 → hundreds digit is 4 → round down → 2000
- Estimate: 3000 + 2000 = 5000

5. 9874 + 3254
- 9874 → hundreds digit is 8 → round up → 10000
- 3254 → 3000
- Estimate: 10000 + 3000 = 13000

6. 3247 + 7841
- 3247 → 3000
- 7841 → hundreds digit is 8 → round up → 8000
- Estimate: 3000 + 8000 = 11000

---

📌 Problem Set 3:

7. 9654 + 3254
- 9654 → hundreds digit is 6 → round up → 10000
- 3254 → 3000
- Estimate: 10000 + 3000 = 13000

8. 4875 + 4214
- 4875 → hundreds digit is 8 → round up → 5000
- 4214 → hundreds digit is 2 → round down → 4000
- Estimate: 5000 + 4000 = 9000

9. 2321 + 1245
- 2321 → hundreds digit is 3 → round down → 2000
- 1245 → hundreds digit is 2 → round down → 1000
- Estimate: 2000 + 1000 = 3000

---

✔ Answers for Section 2 (Nearest Thousand):

| Problem | Rounded Numbers | Estimated Sum |
|---------------|---------------------|---------------|
| 2547 + 3214 | 3000 + 3000 | 6000 |
| 3214 + 1247 | 3000 + 1000 | 4000 |
| 3698 + 2471 | 4000 + 2000 | 6000 |
| 3254 + 2478 | 3000 + 2000 | 5000 |
| 9874 + 3254 | 10000 + 3000 | 13000 |
| 3247 + 7841 | 3000 + 8000 | 11000 |
| 9654 + 3254 | 10000 + 3000 | 13000 |
| 4875 + 4214 | 5000 + 4000 | 9000 |
| 2321 + 1245 | 2000 + 1000 | 3000 |

---

## ✍️ Final Answer Summary:

➤ Nearest Hundred:

```
800, 1500, 500,
500, 600, 1200,
800, 1200, 600
```

➤ Nearest Thousand:

```
6000, 4000, 6000,
5000, 13000, 11000,
13000, 9000, 3000
```

You can fill these into the blanks on your worksheet!

Let me know if you’d like to check the actual sums too — estimation helps us get quick, close answers without exact calculation. 😊