Question

Find and fix the error.
1.9 × 4.4
(10 + 9) × (40 + 4)
(10 × 40) + (10 + 4) + 9x40) + 9 x 4)
14 + 360 + 36
= 450
品x器=鹦
品x#=450

Answer 1

Let's break down the operations step by step and identify any errors present in the calculations.

1. **Original Calculation**: \(1.9 × 4.4\)

To calculate \(1.9 × 4.4\) directly:
- \(1.9 × 4.4 = 8.36\)

2. **Expanded Calculation**:
You wrote:
\[(10 + 9) × (40 + 4)\]

This expands correctly to:
- \((10 + 9) × (40 + 4) = 19 × 44\)

3. **Distribution**:
The next step, which should also use distribution, seems to mix calculations:
\((10 × 40) + (10 × 4) + (9 × 40) + (9 × 4)\)

Calculating those:
- \(10 × 40 = 400\)
- \(10 × 4 = 40\)
- \(9 × 40 = 360\)
- \(9 × 4 = 36\)

Thus, the expansion yields:
\[400 + 40 + 360 + 36\]

4. **Addition**:
Adding those terms:
\[400 + 40 = 440\]
\[440 + 360 = 800\]
\[800 + 36 = 836\]

5. **Final Value**:
The final result should be:
= 836

6. **Comparison**:
You wrote:
= 450, which is incorrect.

In conclusion, the final result of \((10 + 9) × (40 + 4)\) simplifies to 836, not 450.

## Corrected Summary:
1.9 × 4.4 should equal 8.36
And the expanded form \(19 × 44\) correctly calculates to 836.

Please let me know if you need further clarification!