Multiply Decimals worksheet with 20 problems for practice.

Problem Overview:

The task involves multiplying decimals. Each problem consists of two numbers, one of which is a whole number or a decimal, and the other is a decimal. The goal is to calculate the product for each pair.

Solution Approach:

1. Ignore the Decimal Points Initially: Multiply the numbers as if they were whole numbers.
2. Count the Total Number of Decimal Places: Count the total number of digits after the decimal points in both numbers being multiplied.
3. Place the Decimal Point: Place the decimal point in the product so that the total number of decimal places in the product equals the sum of the decimal places in the original numbers.

Step-by-Step Solutions:

#### 1. \( 90 \times 0.8 \)
- Multiply: \( 90 \times 8 = 720 \)
- Decimal places: \( 0.8 \) has 1 decimal place.
- Result: \( 72.0 \) or simply \( 72 \)

#### 2. \( 35 \times 0.07 \)
- Multiply: \( 35 \times 7 = 245 \)
- Decimal places: \( 0.07 \) has 2 decimal places.
- Result: \( 2.45 \)

#### 3. \( 9 \times 0.06 \)
- Multiply: \( 9 \times 6 = 54 \)
- Decimal places: \( 0.06 \) has 2 decimal places.
- Result: \( 0.54 \)

#### 4. \( 35 \times 0.1 \)
- Multiply: \( 35 \times 1 = 35 \)
- Decimal places: \( 0.1 \) has 1 decimal place.
- Result: \( 3.5 \)

#### 5. \( 23 \times 0.2 \)
- Multiply: \( 23 \times 2 = 46 \)
- Decimal places: \( 0.2 \) has 1 decimal place.
- Result: \( 4.6 \)

#### 6. \( 29 \times 0.1 \)
- Multiply: \( 29 \times 1 = 29 \)
- Decimal places: \( 0.1 \) has 1 decimal place.
- Result: \( 2.9 \)

#### 7. \( 11 \times 0.01 \)
- Multiply: \( 11 \times 1 = 11 \)
- Decimal places: \( 0.01 \) has 2 decimal places.
- Result: \( 0.11 \)

#### 8. \( 81 \times 0.06 \)
- Multiply: \( 81 \times 6 = 486 \)
- Decimal places: \( 0.06 \) has 2 decimal places.
- Result: \( 4.86 \)

#### 9. \( 86 \times 0.05 \)
- Multiply: \( 86 \times 5 = 430 \)
- Decimal places: \( 0.05 \) has 2 decimal places.
- Result: \( 4.30 \) or simply \( 4.3 \)

#### 10. \( 89 \times 0.5 \)
- Multiply: \( 89 \times 5 = 445 \)
- Decimal places: \( 0.5 \) has 1 decimal place.
- Result: \( 44.5 \)

#### 11. \( 51 \times 0.04 \)
- Multiply: \( 51 \times 4 = 204 \)
- Decimal places: \( 0.04 \) has 2 decimal places.
- Result: \( 2.04 \)

#### 12. \( 26 \times 0.05 \)
- Multiply: \( 26 \times 5 = 130 \)
- Decimal places: \( 0.05 \) has 2 decimal places.
- Result: \( 1.30 \) or simply \( 1.3 \)

#### 13. \( 78 \times 0.09 \)
- Multiply: \( 78 \times 9 = 702 \)
- Decimal places: \( 0.09 \) has 2 decimal places.
- Result: \( 7.02 \)

#### 14. \( 87 \times 0.07 \)
- Multiply: \( 87 \times 7 = 609 \)
- Decimal places: \( 0.07 \) has 2 decimal places.
- Result: \( 6.09 \)

#### 15. \( 14 \times 0.06 \)
- Multiply: \( 14 \times 6 = 84 \)
- Decimal places: \( 0.06 \) has 2 decimal places.
- Result: \( 0.84 \)

#### 16. \( 57 \times 0.05 \)
- Multiply: \( 57 \times 5 = 285 \)
- Decimal places: \( 0.05 \) has 2 decimal places.
- Result: \( 2.85 \)

#### 17. \( 53 \times 0.4 \)
- Multiply: \( 53 \times 4 = 212 \)
- Decimal places: \( 0.4 \) has 1 decimal place.
- Result: \( 21.2 \)

#### 18. \( 37 \times 0.2 \)
- Multiply: \( 37 \times 2 = 74 \)
- Decimal places: \( 0.2 \) has 1 decimal place.
- Result: \( 7.4 \)

#### 19. \( 54 \times 0.02 \)
- Multiply: \( 54 \times 2 = 108 \)
- Decimal places: \( 0.02 \) has 2 decimal places.
- Result: \( 1.08 \)

#### 20. \( 73 \times 0.8 \)
- Multiply: \( 73 \times 8 = 584 \)
- Decimal places: \( 0.8 \) has 1 decimal place.
- Result: \( 58.4 \)

Final Answers:

\[
\boxed{
\begin{array}{ll}
1. & 72 \\
2. & 2.45 \\
3. & 0.54 \\
4. & 3.5 \\
5. & 4.6 \\
6. & 2.9 \\
7. & 0.11 \\
8. & 4.86 \\
9. & 4.3 \\
10. & 44.5 \\
11. & 2.04 \\
12. & 1.3 \\
13. & 7.02 \\
14. & 6.09 \\
15. & 0.84 \\
16. & 2.85 \\
17. & 21.2 \\
18. & 7.4 \\
19. & 1.08 \\
20. & 58.4 \\
\end{array}
}
\]