Decimal multiplication practice worksheet with 20 problems.

Problem:

The task involves finding the product of pairs of decimal numbers. Below is a step-by-step solution for each problem, along with explanations.

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#### Step 1: Understand the process
To multiply 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 numbers being multiplied.
3. Place the decimal point in the product so that the total number of decimal places matches the sum from step 2.

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Solutions:

#### Problem 1: \( 90 \times 0.8 \)
- Multiply \( 90 \times 8 = 720 \).
- There is 1 decimal place in \( 0.8 \).
- Place the decimal point to get \( 72.0 \).

Answer: \( 72.0 \)

#### Problem 2: \( 35 \times 0.07 \)
- Multiply \( 35 \times 7 = 245 \).
- There are 2 decimal places in \( 0.07 \).
- Place the decimal point to get \( 2.45 \).

Answer: \( 2.45 \)

#### Problem 3: \( 9 \times 0.06 \)
- Multiply \( 9 \times 6 = 54 \).
- There are 2 decimal places in \( 0.06 \).
- Place the decimal point to get \( 0.54 \).

Answer: \( 0.54 \)

#### Problem 4: \( 4 \times 0.1 \)
- Multiply \( 4 \times 1 = 4 \).
- There is 1 decimal place in \( 0.1 \).
- Place the decimal point to get \( 0.4 \).

Answer: \( 0.4 \)

#### Problem 5: \( 23 \times 0.2 \)
- Multiply \( 23 \times 2 = 46 \).
- There is 1 decimal place in \( 0.2 \).
- Place the decimal point to get \( 4.6 \).

Answer: \( 4.6 \)

#### Problem 6: \( 29 \times 0.1 \)
- Multiply \( 29 \times 1 = 29 \).
- There is 1 decimal place in \( 0.1 \).
- Place the decimal point to get \( 2.9 \).

Answer: \( 2.9 \)

#### Problem 7: \( 11 \times 0.01 \)
- Multiply \( 11 \times 1 = 11 \).
- There are 2 decimal places in \( 0.01 \).
- Place the decimal point to get \( 0.11 \).

Answer: \( 0.11 \)

#### Problem 8: \( 81 \times 0.06 \)
- Multiply \( 81 \times 6 = 486 \).
- There are 2 decimal places in \( 0.06 \).
- Place the decimal point to get \( 4.86 \).

Answer: \( 4.86 \)

#### Problem 9: \( 86 \times 0.05 \)
- Multiply \( 86 \times 5 = 430 \).
- There are 2 decimal places in \( 0.05 \).
- Place the decimal point to get \( 4.30 \).

Answer: \( 4.30 \)

#### Problem 10: \( 89 \times 0.5 \)
- Multiply \( 89 \times 5 = 445 \).
- There is 1 decimal place in \( 0.5 \).
- Place the decimal point to get \( 44.5 \).

Answer: \( 44.5 \)

#### Problem 11: \( 51 \times 0.04 \)
- Multiply \( 51 \times 4 = 204 \).
- There are 2 decimal places in \( 0.04 \).
- Place the decimal point to get \( 2.04 \).

Answer: \( 2.04 \)

#### Problem 12: \( 26 \times 0.05 \)
- Multiply \( 26 \times 5 = 130 \).
- There are 2 decimal places in \( 0.05 \).
- Place the decimal point to get \( 1.30 \).

Answer: \( 1.30 \)

#### Problem 13: \( 78 \times 0.09 \)
- Multiply \( 78 \times 9 = 702 \).
- There are 2 decimal places in \( 0.09 \).
- Place the decimal point to get \( 7.02 \).

Answer: \( 7.02 \)

#### Problem 14: \( 87 \times 0.07 \)
- Multiply \( 87 \times 7 = 609 \).
- There are 2 decimal places in \( 0.07 \).
- Place the decimal point to get \( 6.09 \).

Answer: \( 6.09 \)

#### Problem 15: \( 14 \times 0.06 \)
- Multiply \( 14 \times 6 = 84 \).
- There are 2 decimal places in \( 0.06 \).
- Place the decimal point to get \( 0.84 \).

Answer: \( 0.84 \)

#### Problem 16: \( 57 \times 0.05 \)
- Multiply \( 57 \times 5 = 285 \).
- There are 2 decimal places in \( 0.05 \).
- Place the decimal point to get \( 2.85 \).

Answer: \( 2.85 \)

#### Problem 17: \( 53 \times 0.4 \)
- Multiply \( 53 \times 4 = 212 \).
- There is 1 decimal place in \( 0.4 \).
- Place the decimal point to get \( 21.2 \).

Answer: \( 21.2 \)

#### Problem 18: \( 37 \times 0.2 \)
- Multiply \( 37 \times 2 = 74 \).
- There is 1 decimal place in \( 0.2 \).
- Place the decimal point to get \( 7.4 \).

Answer: \( 7.4 \)

#### Problem 19: \( 54 \times 0.02 \)
- Multiply \( 54 \times 2 = 108 \).
- There are 2 decimal places in \( 0.02 \).
- Place the decimal point to get \( 1.08 \).

Answer: \( 1.08 \)

#### Problem 20: \( 73 \times 0.8 \)
- Multiply \( 73 \times 8 = 584 \).
- There is 1 decimal place in \( 0.8 \).
- Place the decimal point to get \( 58.4 \).

Answer: \( 58.4 \)

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Final Answers:

\[
\boxed{
\begin{array}{ll}
1. & 72.0 \\
2. & 2.45 \\
3. & 0.54 \\
4. & 0.4 \\
5. & 4.6 \\
6. & 2.9 \\
7. & 0.11 \\
8. & 4.86 \\
9. & 4.30 \\
10. & 44.5 \\
11. & 2.04 \\
12. & 1.30 \\
13. & 7.02 \\
14. & 6.09 \\
15. & 0.84 \\
16. & 2.85 \\
17. & 21.2 \\
18. & 7.4 \\
19. & 1.08 \\
20. & 58.4 \\
\end{array}
}
\]