Millimeters or microns are measured with rulers or micrometers. Depends what you are doing.
Kilometers are a unit of length, used to measure distance.
You would use a length/distance unit, such as meters or kilometers.
By unit of length and distance and conversion ,we can say that cm is used to measure length of a finger
length and distance
Miles or kilometers.
By unit of length and distance and conversion ,we can say that units are used to measure length are meters ,cm,dm,dam,mm
Yes, the ruler does need to be straight when finding or measuring the length of a country on a map. If the distance curved, you can use a string and the ruler to measure the length.
Miles is best.
Miles or kilometers
It depends on what you want to measure. A unit that is suitable for the distance between subatomic particles will be of little use in measuring intergalactic distances (and conversely).
This depends on the length of the object.You can use mm for very short objects, cm for short objects, m for long objects; and working with a microscope we use μm.
To measure length or distance. One meter is 3.28 feet or roughly one yard.