Here are useful units of measure to know

Length
Metric System		English System
1 meter (m)	= 1000 millimeters (mm)	1 foot (ft)	= 12 inches (in)
1 meter (m)	= 100 centimeters (cm)	1 yard (yd)	= 3 feet or 36 inches
1 kilometer (km)	= 1000 meters (m)	1 mile (mi)	= 1760 yards or 5280 feet
1 centimeter (cm)	= 10 millimeters (mm)
	2.54 centimeters (cm)	= 1 inch (in)

Example 1: Unit conversion (metric system)

Do the following conversions. Round to nearest tenth where necessary.
9,000 mm³ = cm³

We know that 10 mm = 1 cm. To convert mm³ to cm³,

(10 mm)3	=	(1 cm)3
103 mm3	=	13 cm3
1000 mm3	=	1 cm3

Now convert 9,000 mm³ to cm³.

9,000 mm3	=	9,000 mm3 ×
	=	9,000 mm3 ×
	=	9 cm3

The answer is 9,000 mm³ = cm³

Example 2: Unit conversion (English system)

Do the following conversions. Round to nearest tenth where necessary.
5 ft² = in²

We know that 1 ft = 12 in. To convert ft² to in²,

(1 ft)2	=	(12 in)2
12 ft2	=	122 in2
1 ft2	=	144 in2

Now convert 5 ft² to in².

5 ft2	=	5 ft2 ×
	=	5  ft2  ×
	=	720 in2

The answer is 5 ft² = in²