Estimating Decimals worksheet for practicing rounding and multiplication.

Let's solve the problem step by step.

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Task:

Estimate the product of each decimal multiplication problem by rounding each decimal to the nearest whole number before multiplying.

We'll go through each problem and:
1. Round each decimal to the nearest whole number.
2. Multiply the rounded numbers.
3. Write the estimated product.

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Rounding Rules:

- If the decimal part is 0.5 or more, round up.
- If it's less than 0.5, round down.

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Now, let’s solve each one:

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1.
42.18 → 42 (since 0.18 < 0.5)
21.56 → 22 (since 0.56 ≥ 0.5)
→ 42 × 22 = 924 ✔

2.
34.18 → 34
17.24 → 17
→ 34 × 17 = 578

3.
27.34 → 27
33.27 → 33
→ 27 × 33 = 891

4.
37.51 → 38 (0.51 ≥ 0.5)
21.45 → 21
→ 38 × 21 = 798

5.
31.33 → 31
15.12 → 15
→ 31 × 15 = 465

6.
12.67 → 13 (0.67 ≥ 0.5)
10.87 → 11 (0.87 ≥ 0.5)
→ 13 × 11 = 143

7.
87.71 → 88 (0.71 ≥ 0.5)
34.45 → 34
→ 88 × 34 = 2992

8.
76.56 → 77 (0.56 ≥ 0.5)
45.33 → 45
→ 77 × 45 = 3465

9.
34.76 → 35 (0.76 ≥ 0.5)
17.87 → 18 (0.87 ≥ 0.5)
→ 35 × 18 = 630

10.
24.78 → 25 (0.78 ≥ 0.5)
14.12 → 14
→ 25 × 14 = 350

11.
35.67 → 36 (0.67 ≥ 0.5)
17.45 → 17
→ 36 × 17 = 612

12.
25.33 → 25 (0.33 < 0.5)
10.12 → 10
→ 25 × 10 = 250

13.
38.54 → 39 (0.54 ≥ 0.5)
12.16 → 12
→ 39 × 12 = 468

14.
28.87 → 29 (0.87 ≥ 0.5)
19.13 → 19
→ 29 × 19 = 551

15.
39.78 → 40 (0.78 ≥ 0.5)
15.32 → 15
→ 40 × 15 = 600

16.
28.67 → 29 (0.67 ≥ 0.5)
15.34 → 15
→ 29 × 15 = 435

17.
23.78 → 24 (0.78 ≥ 0.5)
17.33 → 17
→ 24 × 17 = 408

18.
35.37 → 35 (0.37 < 0.5)
19.23 → 19
→ 35 × 19 = 665

19.
12.29 → 12 (0.29 < 0.5)
27.52 → 28 (0.52 ≥ 0.5)
→ 12 × 28 = 336

20.
23.57 → 24 (0.57 ≥ 0.5)
19.32 → 19
→ 24 × 19 = 456

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✔ Final Answers (Estimated Products):

| Problem | Rounded Numbers | Estimated Product |
|--------|------------------|-------------------|
| 1 | 42 × 22 | 924 |
| 2 | 34 × 17 | 578 |
| 3 | 27 × 33 | 891 |
| 4 | 38 × 21 | 798 |
| 5 | 31 × 15 | 465 |
| 6 | 13 × 11 | 143 |
| 7 | 88 × 34 | 2992 |
| 8 | 77 × 45 | 3465 |
| 9 | 35 × 18 | 630 |
| 10 | 25 × 14 | 350 |
| 11 | 36 × 17 | 612 |
| 12 | 25 × 10 | 250 |
| 13 | 39 × 12 | 468 |
| 14 | 29 × 19 | 551 |
| 15 | 40 × 15 | 600 |
| 16 | 29 × 15 | 435 |
| 17 | 24 × 17 | 408 |
| 18 | 35 × 19 | 665 |
| 19 | 12 × 28 | 336 |
| 20 | 24 × 19 | 456 |

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✔ Summary:

You estimate the product by rounding each decimal to the nearest whole number and then multiplying those whole numbers. This gives a quick approximation of the actual product.

Let me know if you'd like the exact products for comparison!