How to convert 42 millimeters to inches?
We know (by definition) that:
We can set up a proportion to solve for the number of inches.
Now, we cross multiply to solve for our unknown :
Conversion in the opposite direction
The inverse of the conversion factor is that 1 inch is equal to 0.604761904761905 times 42 millimeters.
It can also be expressed as: 42 millimeters is equal to inches.
An approximate numerical result would be: forty-two millimeters is about one point six four inches, or alternatively, a inch is about zero point six zero times forty-two millimeters.
 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.