Estimating Sums Worksheets - 15 Worksheets Library - Free Printable

Let’s solve this step by step.

We are asked to estimate addition problems by rounding numbers — first to the nearest hundred, then to the nearest thousand.

---

Part 1: Round to the nearest hundred

Rule: Look at the tens digit.
- If it’s 5 or more → round up.
- If it’s less than 5 → round down.

Let’s do each problem:

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

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 (tens=6)
- 247 → 200 (tens=4)
→ Estimate: 400 + 200 = 600

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

7. 632 + 247
- 632 → tens=3 → round down → 600
- 247 → tens=4 → round down → 200
→ Estimate: 600 + 200 = 800

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

9. 365 + 247 ← same as #5 → 600

Wait — let me check if I missed any. The worksheet has 9 problems in Part 1? Let me recount from the image layout:

Actually, looking again — there are 3 columns × 3 rows = 9 problems for “nearest hundred”.

I did all 9 above. Good.

---

Part 2: Round to the nearest thousand

Rule: Look at the hundreds digit.
- If it’s 5 or more → round up.
- If it’s less than 5 → round down.

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

2. 3214 + 1247
- 3214 → hundreds=2 → 3000
- 1247 → hundreds=2 → 1000
→ Estimate: 3000 + 1000 = 4000

3. 3698 + 2471
- 3698 → hundreds=6 → 4000
- 2471 → hundreds=4 → 2000
→ Estimate: 4000 + 2000 = 6000

4. 3254 + 2478
- 3254 → hundreds=2 → 3000
- 2478 → hundreds=4 → 2000
→ Estimate: 3000 + 2000 = 5000

5. 9874 + 3254
- 9874 → hundreds=8 → 10000
- 3254 → hundreds=2 → 3000
→ Estimate: 10000 + 3000 = 13000

6. 3247 + 7841
- 3247 → hundreds=2 → 3000
- 7841 → hundreds=8 → 8000
→ Estimate: 3000 + 8000 = 11000

7. 9654 + 3254
- 9654 → hundreds=6 → 10000
- 3254 → hundreds=2 → 3000
→ Estimate: 10000 + 3000 = 13000

8. 4875 + 4214
- 4875 → hundreds=8 → 5000
- 4214 → hundreds=2 → 4000
→ Estimate: 5000 + 4000 = 9000

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

---

Now let’s write all answers clearly in order.

Final Answer:
Estimate by rounding to nearest hundred:
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

Estimate by rounding to nearest thousand:
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