Sure! Let’s solve each of the 16 multiplication problems step by step. The goal is to multiply two decimal numbers and place the decimal point correctly in the product.
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General Rule for Multiplying Decimals:
1. Ignore the decimal points and multiply the numbers as if they were whole numbers.
2. Count the total number of decimal places in both factors.
3. Place the decimal point in the product so that it has the same number of decimal places as the total from step 2.
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Let’s solve each problem:
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① 23.4 × 4.2
- Multiply 234 × 42 = 9828
- 23.4 has 1 decimal, 4.2 has 1 → total 2 decimals
- Product:
98.28
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② 76.5 × 2.4
- 765 × 24 = 18360
- 76.5 (1) + 2.4 (1) = 2 decimals
- Product:
183.60 → can write as
183.6
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③ 9.2 × 5.3
- 92 × 53 = 4876
- 9.2 (1) + 5.3 (1) = 2 decimals
- Product:
48.76
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④ 64.5 × 2.2
- 645 × 22 = 14190
- 64.5 (1) + 2.2 (1) = 2 decimals
- Product:
141.90 →
141.9
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⑤ 18.2 × 3.6
- 182 × 36 = 6552
- 18.2 (1) + 3.6 (1) = 2 decimals
- Product:
65.52
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⑥ 14.5 × 0.3
- 145 × 3 = 435
- 14.5 (1) + 0.3 (1) = 2 decimals
- Product:
4.35
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⑦ 36.8 × 8.5
- 368 × 85 = 31280
- 36.8 (1) + 8.5 (1) = 2 decimals
- Product:
312.80 →
312.8
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⑧ 3.9 × 6.4
- 39 × 64 = 2496
- 3.9 (1) + 6.4 (1) = 2 decimals
- Product:
24.96
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⑨ 0.5 × 7.4
- 5 × 74 = 370
- 0.5 (1) + 7.4 (1) = 2 decimals
- Product:
3.70 →
3.7
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⑩ 86.5 × 6.2
- 865 × 62 = 53630
- 86.5 (1) + 6.2 (1) = 2 decimals
- Product:
536.30 →
536.3
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⑪ 29.5 × 4.6
- 295 × 46 = 13570
- 29.5 (1) + 4.6 (1) = 2 decimals
- Product:
135.70 →
135.7
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⑫ 63.2 × 5.8
- 632 × 58 = 36656
- 63.2 (1) + 5.8 (1) = 2 decimals
- Product:
366.56
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⑬ 2.4 × 0.7
- 24 × 7 = 168
- 2.4 (1) + 0.7 (1) = 2 decimals
- Product:
1.68
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⑭ 8.9 × 1.6
- 89 × 16 = 1424
- 8.9 (1) + 1.6 (1) = 2 decimals
- Product:
14.24
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⑮ 47.2 × 5.3
- 472 × 53 = 24976
- 47.2 (1) + 5.3 (1) = 2 decimals
- Product:
249.76
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⑯ 63.2 × 5.8 ← Wait — this is a repeat of #12!
We already solved it:
366.56
*(Note: Probably a typo in worksheet — maybe meant another problem? But we’ll go with what’s written.)*
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✔ Final Answers:
| Problem | Answer |
|---------|------------|
| ① | 98.28 |
| ② | 183.6 |
| ③ | 48.76 |
| ④ | 141.9 |
| ⑤ | 65.52 |
| ⑥ | 4.35 |
| ⑦ | 312.8 |
| ⑧ | 24.96 |
| ⑨ | 3.7 |
| ⑩ | 536.3 |
| ⑪ | 135.7 |
| ⑫ | 366.56 |
| ⑬ | 1.68 |
| ⑭ | 14.24 |
| ⑮ | 249.76 |
| ⑯ | 366.56 |
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💡 Tip for Students:
Always count decimal places carefully! You can check your answer by estimating — for example, 23.4 × 4.2 should be close to 20 × 4 = 80, so 98.28 makes sense.
Let me know if you’d like a printable answer key or step-by-step work shown for any specific problem!
Parent Tip: Review the logic above to help your child master the concept of double digit multiplication with decimals worksheet.
