Why is the metric system of measurement based on multiples of 10?

Answer 1

Metric is based on all units and subunits being multiples of 10. For instance:

1 km = 1,000 m = 100,000 cm = 1,000,000 mm = 1,000,000,000 nm and so on

these same numbers can be expressed in base 10 as follows:

1 km = 103 m = 105 cm = 106 mm = 109 nm where the power varies directly with the units being expressed. For instance, how many km is the Olympic 1500 m? 1.5 km

To solve we convert 1500 m to a base 10 expression of 1.5 x 103 m = 1.5 km

by contrast you cannot easily do the same for the 1 mile run (1600 m) because

1 mile = 5280 feet = 63360 inches which requires knowing the various conversion factors such as 12 inches per foot

other examples include volume

1 L = 103 mL (try to do this easily in gallons and ounces)

and mass 1 metric tonne = 103 kg = 106 g = 109 ug (where u is the Greek symbol mu)

Answer 2

It is not multiples of 10; it is powers of 10. The reason for this is that calculating with powers of 10 is extremely simple (for us, since we are accustomed to work in base 10). For example, to convert kilometers to meters, just add three zeroes (or, if it is a number with decimals, move the decimal point three positions to the right). For example, 23 kilometers is 23,000 meters, while 4.2 kilometers are 4200 meters. To convert to millimeters, add six zeroes, or move the decimal point six places. With a little practice, these calculations can be done in your head. Now, try converting 23 miles, or 4.2 miles, to yards, then to feet, then to inches. (I even have trouble remembering how many feet there are in a mile.)