Which measurements are you talking about? I have to admit, I kind of cheat - I use one of those measurement conversion websites, I've put it in the related links.
The answer depends on what measurement the conversion concerns. There is no way that you can convert a measurement of mass to degrees, for example.
You do not convert. STERADIAN is a two dimensioal measurement RADIAN is a one dimensional measurement. Just as you cannot convert area into degrees (of angular measurement)
You don't. You can convert one square measurement into another - for example, square yards into square feet. You can't convert an arbitrary number (without a measurement) into a measurement.
You cannot convert ounces to kilometers. Ounces are a measurement of weight. Kilometers are a measurement of distance.
What are the likely maximum and minimum values for this measurement 20.4+_0.1cm
No. The metric system, since it is based on powers of ten, is better used with decimal representations of values.
You can't convert the two. One is measurement of weight, and the other is a measurement of mass.
Significant figures indicate the precision of a measurement.
distance
It is impossible to convert a measurement of time into a measurement of length.
You can't. Feet are a measurement of length. Kilograms are a measurement of mass.
You cannot convert m2 to m3 without a third measurement as a cubic measurement is width plus length pus depth.