20 inch
You can invent any number of nonstandard units, but none of them is "best". It is best to use standard units, that is, the meter.
The best measurement to use when measuring the width of a house fly is millimeters. This unit is precise enough to capture the small size of the fly, which typically measures about 6 to 7 millimeters in width. Using a ruler or caliper that can measure in millimeters will provide the most accurate results for such a small insect.
4-5 1/2 meters
An inch is roughly equivalent to the width of an adult thumb, but this can vary from person to person. Typically, many people find that their thumb is about 1 inch wide, making it a useful informal measurement. However, for precise measurements, it's best to use a ruler or measuring tape.
Whole numbers are the best representation of students.
Well, sweetheart, the best estimate for the width of a classroom would typically be around 20 to 25 feet wide. But hey, if you want to get fancy with it, you can always whip out a measuring tape and get the exact number. Just make sure to watch out for any lurking dust bunnies while you're at it.
Answer: meters
200mm
Best measurement for a phone book is cm or inches.
A millimetre.
milimeters
9 cm
You can invent any number of nonstandard units, but none of them is "best". It is best to use standard units, that is, the meter.
It's Yard
in miles
The metric measurement that is the best estimate for the length of a car is typically in meters or centimeters. This allows for a more precise measurement compared to using larger units such as kilometers.
Inches or centimeters.