How to convert 21 yards to millimeters?
We know (by definition) that:
We can set up a proportion to solve for the number of millimeters.
Now, we cross multiply to solve for our unknown :
Conversion in the opposite direction
The inverse of the conversion factor is that 1 millimeter is equal to 5.2076823730367e-05 times 21 yards.
It can also be expressed as: 21 yards is equal to millimeters.
An approximate numerical result would be: twenty-one yards is about zero millimeters, or alternatively, a millimeter is about zero times twenty-one yards.
 The precision is 15 significant digits (fourteen digits to the right of the decimal point).Results may contain small errors due to the use of floating point arithmetic.