840 millimeters in decimeters

Conversion formula
How to convert 840 millimeters to decimeters?

We know (by definition) that: $1\mathrm{mm}=0.01\mathrm{dm}$

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

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

Conclusion: 840 ⁢ mm = 8.4 ⁢ dm

Conversion in the opposite direction

The inverse of the conversion factor is that 1 decimeter is equal to 0.119047619047619 times 840 millimeters.

It can also be expressed as: 840 millimeters is equal to $\frac{1}{\mathrm{0.119047619047619}}$ decimeters.

Approximation

An approximate numerical result would be: eight hundred and forty millimeters is about zero decimeters, or alternatively, a decimeter is about zero point one two times eight hundred and forty millimeters.