6 m would be used to measure flagpole. 600 m is a bigger unit.
miles
inches
gallons
you would use gallons to measure the capacity of a bathtub
measured in kg
Meter, kilometer is the SI equivalent to the mile.
Metres.
I would use Meters
One of length. I'd go for Metres and Centimetres but you could use Feet and/or Yards. Or declare a new unit of "Flagpole" which is exactly one flagpole long....
It depends on the relative height of the flagpole. If it's short, like a flag mast on a boat or building, probably feet and inches would do. If it's very tall, like the flagpole on top of a building or monument, yards and feet might be more appropriate.
division
The Unit Used To Measure A Train Can Be Kilometer.
miles
cm
What measure of units would you use to measure the thickness of a phone book
Which unit would you use to measure the water in a full tub?
Feet