0.4 sq.cm is____sq. km

Options

A. `4xx10^(-10)`
B. `4xx10^(-11)`
C. `0.4x×10^(-11)`
D. `4xx10^(-9)`

Answer

To convert 0.4 square centimeters (sq. cm) to square kilometers (sq. km), we will follow these steps:

### Step 1: Understand the conversion factors
1 kilometer (km) is equal to 1000 meters (m), and 1 meter is equal to 100 centimeters (cm). Therefore, we can calculate how many centimeters are in 1 kilometer:
- 1 km = 1000 m = 1000 × 100 cm = 100,000 cm = 10^5 cm.

### Step 2: Calculate the area conversion
Since we are dealing with square units, we need to square the conversion factor:
- 1 km² = (10^5 cm)² = 10^10 cm².

### Step 3: Find the conversion for 1 cm²
To find how many square kilometers are in 1 square centimeter, we take the reciprocal of the area conversion:
- 1 cm² = 1 / (10^10 km²) = 10^(-10) km².

### Step 4: Convert 0.4 cm² to km²
Now we can convert 0.4 cm² to km² by multiplying by the conversion factor we found in Step 3:
- 0.4 cm² = 0.4 × 10^(-10) km².

### Step 5: Simplify the expression
To express this in standard form:
- 0.4 × 10^(-10) km² = 4 × 10^(-1) × 10^(-10) km² = 4 × 10^(-11) km².

### Final Answer
Thus, 0.4 sq. cm is equal to 4 × 10^(-11) sq. km.

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