Powers of 10 and Scientific Notation
109 = 1,000,000,000 = 1 billion (giga, G)

106 = 1,000,000 = 1 million (mega, M)

103 = 1,000 = 1 thousand (kilo, k)

102 = 100 = 1 hundred (hecto, h)

101 = 10 = ten = (deca)

10-9 = 0.000000001 = 1 billionth (nano, n)

10-6 = 0.000001 = 1 millionth (micro, m)

10-3 = 0.001 = 1 thousandth (milli, m)

10-2 = 0.01 = 1 hundreth (centi, c)

10-1 = 0.1 = 1 tenth (deci)

3.78 x 106 = 3,780,000

10,560 = 10.56 x 104

1.23 x 10-4 = 0.000123

0.045 = 4.5 x 10-2

Length
1 meter (m) = 100 centimeters (cm) = 1000 millimeters (mm) = 106 micrometers (mm) = 109 nanometers (nm)
1 kilometer (km) = 1000 m = 0.6214 mile (mi)
1 m = 3.281 feet (ft) = 39.37 inches (in)
1 cm = 0.3937 in
1 ft = 30.48 cm
1 in = 2.540 cm
1 mi = 5280 ft = 1.609 km

Volume
1 liter = 1000 cm3 = 10-3 m3 = 0.0351 ft3 = 61.02 in3
1 ft3 = 0.02832 m3 = 28.32 liters = 7.477 gallons

Time
1 minute = 60 seconds (s)
1 hour (hr) = 60 minutes = 3600 s
1 day = 86,400 s
1 year (yr) = 365 days = 3.156 x 107 s

Mass
1 kilogram (kg) = 103 gram (g) = 0.0685 slug*
1 g = 6.85 x 10-5 slug
1 kg = 2.2046 "pounds"*

*A kg is a unit of mass. A slug is a unit of mass. A pound is technically a unit of force. Conventionally, we use a pound as a unit of mass, and thus we provide the third conversion factor above for convenience.

Temperature
1 degree Celsius (°C) = (°F - 32)/1.8
1°F = (1.8 x °C) + 32