mm or cm.. I'm sure both would be accepted.
I would use millimetres to measure the diameter of a thumbtack (commonly known as a drawing pin in the UK). The instrument depends on whether you want the length, in which case a ruler will work, or the width of the shaft, where a vernier caliper or micrometer would be better.
You would use millimeters to measure the length of a thumb tack
for metric units centimeters. for customary inches
That would depend on the size of whatever it is you're measuring.
You can use any unit of length/distance, such as meters or millimeters.
A micrometre
meters
millimeters
Meters
(g) grams- is the unit used in the metric system.
kilograms
The main unit in the metric system is the meter. It measures length.
Width is a length or distance. The unit of length is the meter.
mm
millimetres (or tenths of millimetres, if you have a micrometer)
The width of a pencil would be the metric unit of centimeters
(g) grams- is the unit used in the metric system.
The Newton.
grams
kilograms
5 km
The main unit in the metric system is the meter. It measures length.
Width is a length or distance. The unit of length is the meter.
The 'kilometer' is a unit of length or distance in the metric system.
centimeter
The litre