The area of a rectangular room is 40 sq. m. Express the area of the room in sq. km.

Answer

To solve the problem of converting the area of a rectangular room from square meters to square kilometers, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Area**:
The area of the rectangular room is given as:
\[ \text{Area} = 40 \, \text{m}^2 \]

2. **Understand the Conversion Factor**:
We need to convert square meters to square kilometers. We know that:
\[ 1 \, \text{km} = 1000 \, \text{m} \]
Therefore, when we square this relationship to convert square meters to square kilometers:
\[ 1 \, \text{km}^2 = (1000 \, \text{m})^2 = 1000^2 \, \text{m}^2 = 1,000,000 \, \text{m}^2 \]
This means:
\[ 1 \, \text{km}^2 = 10^6 \, \text{m}^2 \]

3. **Convert Square Meters to Square Kilometers**:
To convert the area from square meters to square kilometers, we can use the conversion factor:
\[ 1 \, \text{m}^2 = \frac{1}{10^6} \, \text{km}^2 \]
Therefore, to convert 40 m² to km²:
\[ 40 \, \text{m}^2 = 40 \times \frac{1}{10^6} \, \text{km}^2 = \frac{40}{10^6} \, \text{km}^2 \]

4. **Simplify the Expression**:
Now, simplify the fraction:
\[ \frac{40}{10^6} = \frac{40}{1000000} = 0.00004 \, \text{km}^2 \]

5. **Final Result**:
Therefore, the area of the rectangular room in square kilometers is:
\[ \text{Area} = 0.00004 \, \text{km}^2 \]

### Summary:
The area of the room is \(0.00004 \, \text{km}^2\).