After you measure the width of the door, you can use any unit of length you like
to describe it. No unit is 'correct' or incorrect, but there's always one that produces
the most convenient number ... the number that's easiest to write down, remember,
and tell other people about.
For the width of a door, I think inches would be a bit more convenient than feet.
millimetres or even micrometres.
Pencil lead is very narrow. Millimeter can be used to measure it.
Metres, to measure its length or width, square metres to measure its area.
mm
Kilometers would be the most likely choice.
the metric system
centimeters
METERS!!!The unit of measurement you would use to measure the width of your classroom is meters.
Centimetre.
Parsecs
Calculation is doomed to fail. The correct approach is to measure them.
It is still customary to measure, in inches, a screen from corner to corner diagonally.
a ruler
Millimetres
Identify the SI until you would use the measured the width of your classroom
The answer depends on which characteristic you wish to measure: its diameter, volume, mass, weight, etc.
15 m