21 centimeters in kilometers

Result

The conversion result is: 21 centimeters is equivalent to 0.00021 kilometers.^[1]

Conversion formula
How to convert 21 centimeters to kilometers?

We know (by definition) that: 1 cm = 1e-05 km.

We can set up a proportion to solve for the number of kilometers.

1 cm / 21 cm = 1e-05 km / x km

Now, we cross multiply to solve for our unknown x:

x km = (21 cm / 1 cm) * 1e-05 km → x km = 0.00021 km

Conclusion:

21 cm = 0.00021 km

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer is equal to 4761.90476190476 times 21 centimeters.

It can also be expressed as: 21 centimeters is equal to 1 / 4761.90476190476 kilometers.

Approximation

An approximate numerical result would be: twenty-one centimeters is about zero kilometers, or alternatively, a kilometer is about four thousand, seven hundred and sixty-one point eight nine times twenty-one centimeters.