## Metric systems

The traditional metric unit of size is the meter , which is a bit longer 보다 3 feet.

(The precise length that a meter is characterized by the international Bureau of Weights and Measures together the length of the path travelled by irradiate in vacuum during a very short interval of time, namely 1 299972458 the a second. Don"t worry, girlfriend will probably never have to remember this!)

native the meter, we acquire the remainder of the metric units using the typical metric prefixes.

 nanometer(nm) 1 1 , 000 , 000 , 000 that a meter micrometer(um) 1 1 , 000 , 000 the a meter millimeter(mm) 1 1000 of a meter centimeter(cm) 1 100 of a meter decimeter(dm) 1 10 of a meter meter(m) 1 meter dekameter(dam) 10 meters hectometer(hm) 100 meters kilometer(km) 1000 meters Megameter(Mm) 1,000,000 meter Gigameter(Gm) 1,000,000,000 meters Terameter(Tm) 1,000,000,000,000 meter

Metric rulers room usually have centimeters numbered, with smaller marks displayed for millimeters. The pencil in the figure has a size of 3.4 centimeters, or 34 millimeters.

## U.S. Customary units

The system for measuring size in the customary device is based on the inch, foot, yard, and mile.

1     foot   ( ft )             =     12   customs     ( in . ) 1     yard     ( yd )     =     3   feet 1     mile     (mi)       =     5,280     feet

Lengths smaller sized than 1 inch room usually written using fractions of one inch. On a U.S. Customary foot ruler, the inch is usually separated into halves, quarters, eighths, and also sixteenths by progressively smaller markings. In the number shown, the pencil is 2 5 16 inch long.

To transform native one unit come another, we can use unit analysis . Because that instance, if you desire to uncover the variety of inches in 3 miles, you deserve to multiply the amount 3 miles by the portion 5280     feet / 1 mile and then by the fraction 12     inch / 1 foot.

1     mile = 5 , 280     feet 1     foot = 12     customs 12     inch     ×     5 , 280     feet = 63 , 360 inches in 1 mile

To discover the number of inches in 3 miles:

3 × 5280     feet 1     mile × 12 1     foot = 190080     inch

(Both this fractions room equal come 1 , for this reason you"re not an altering the original quantity once you multiply.)

Note:

(a) To convert from larger units to smaller sized units, main point by the appropriate unit ratio.

(b) To convert from smaller sized units to bigger units, main point by the mutual the the ideal unit ratio.

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(c) multiplying or splitting by a unit ratio is mathematically identical to making use of a ratio to convert between units of measure .