Explanation:
The point of this exercise is to give you an appreciation of the fact that metric length units are related by powers of 10. This means units conversion generally consists only of adjustment of the decimal point, or the power of 10 (for numbers in scientific notation).
For example, ...
1 cm = 10 mm
1 dm = 10 cm
1 m = 10 dm = 100 cm = 1000 mm
1 km = 1000 m
The prefixes m, c, d, k are standard SI prefixes applicable to other SI units as well.
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On the other hand, "customary" US units have relationships that are not powers of 10:
1 ft = 12 in
1 yd = 3 ft
1 rod = 5.5 yd
1 chain = 4 rods
1 furlong = 10 chains = 220 yards
1 mile = 8 furlongs = 1760 yards = 5280 feet
(Inches, feet, and miles are in common use; yards perhaps less so. Furlongs are rarely seen outside of horse racing, or the whimsical speed unit "furlongs per fortnight"—11/28 inch per minute.)
So, conversion from one unit of US customary measure to another involves conversion factors that are not always easily remembered.
