21 centimeters in decimeters

Conversion formula
How to convert 21 centimeters to decimeters?

We know (by definition) that: $1\mathrm{cm}=0.1\mathrm{dm}$

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

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

Conclusion: 21 ⁢ cm = 2.1 ⁢ dm

Conversion in the opposite direction

The inverse of the conversion factor is that 1 decimeter is equal to 0.476190476190476 times 21 centimeters.

It can also be expressed as: 21 centimeters is equal to $\frac{1}{\mathrm{0.476190476190476}}$ decimeters.

Approximation

An approximate numerical result would be: twenty-one centimeters is about zero decimeters, or alternatively, a decimeter is about zero point four eight times twenty-one centimeters.