21 feet in decimeters

Conversion formula
How to convert 21 feet to decimeters?

We know (by definition) that: $1\mathrm{ft}=3.048\mathrm{dm}$

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 ⁢ ft = 64.008 ⁢ dm

Conversion in the opposite direction

The inverse of the conversion factor is that 1 decimeter is equal to 0.0156230471191101 times 21 feet.

It can also be expressed as: 21 feet is equal to $\frac{1}{\mathrm{0.0156230471191101}}$ decimeters.

Approximation

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