The answer depends on the length of the line - in any units of measurement.
each little line is a millimeter and there are 10 millimeters in a centimeter. So the second line would be 2 millimeters
500 millimeters or 500 mm.
A ruler ?
No, they are not.
1000 meters
meter
365 days
look below
The meter.
50
150 mm
if its a line it goes on forever so it has arrows on each end. For a segment you just make a dot, measure 46 millimeters and put another dot on that end. No arrows on a segment.