Unit Names for Numerical Questions
Many different unit names and abbreviations can be used in numerical questions requiring units.
Rules for Units
Observe the following rules when specifying units.
Rule | Incorrect | Correct |
---|---|---|
Type a space between the number and the unit. | 20g 20 g |
20 g |
Units are case-sensitive. | 1 minute = 60 S | 1 minute = 60 s |
Do not combine multiple values and units. | 3 minutes 15 seconds | 3.25 minutes |
To change the dimension of a unit, follow the unit with a caret (^) and an exponent. Do not use the words "square" or "cubic." Do not use two asterisks (**) to specify the exponent. | 3 square miles 3 mi**2 |
3 mi^2 |
To divide a unit, use /. Do not use "per." | miles per hour | miles/hour |
To multiply a unit, use a space or asterisk. Do not use a raised dot or hyphen. | kW·h kilowatt-hour |
kW*h kilowatt hour |
Many unit names accept singular and plural forms interchangeably. Do not pluralize unit abbreviations. | 3 mis | 3 mi 3 miles |
Do not enter a fraction for the number when units are required. | 3/4 inch | 0.75 inch |
Units
This is not an exhaustive list, but includes the most commonly used units and abbreviations. For SI units, most derived units are not listed here.
Note: For units having different values in different countries, the U.S. value is
used.
Unit | Abbreviation | Notes |
---|---|---|
ampere | A | |
angstrom | Å, ångström | |
astronomicalunit | au, AU | |
atmosphere | atm | |
atomicmassunit | u, amu | |
bar | ||
becquerel | Bq | |
britishthermalunit | btu | |
bushel | bu | |
calorie | cal | |
carat | ct | |
cc | Cubic centimeter. Do not use cubic centimeter. | |
cm^3 | Cubic centimeter. Do not use cubic centimeter. | |
coulomb | C | |
cup | ||
curie | Ci | |
day | d | |
diopter | The alternative spelling "dioptre" can also be used. | |
dollar | $ | The unit must follow the number, as in 3.25 $. Do not specify $3.25. |
farad | F | |
foot | ft | Alternatively, feet. |
foot^3/second | cfs | |
gallon/hour | gal/h, gph | |
gallon | gal | |
grain | gr | |
gram | g, gm | |
henry | H | |
hertz | Hz, hz | |
horsepower | hp | |
hour | h, hr | |
inch | in | |
joule | J | |
kilocalorie | Calorie | |
kilogram | kg | |
kilometer/hour | kph | |
kilowatt hour | kWh | |
liter/minute | lpm | |
liter/hour | L/h | |
liter | L | The alternative spelling "litre" can also be used. |
meter | m | The alternative spelling "metre" can also be used. |
micron | ||
microsecond | µs, us | |
mile/gallon | mpg | |
mile/hour | mph | |
mile | mi | |
minute | min | Use for time only. |
mmHg | ||
molar | M | |
mole | mol | |
newton | N | |
ohm | You cannot use the Ω character. | |
ounce | oz | |
partsperbillion | ppb | Uses U.S. definition: 10^{-9}. |
partspermillion | ppm | Uses U.S. definition: 10^{-6}. |
partspertrillion | ppt | Uses U.S. definition: 10^{-12}. |
pascal | Pa, pa | |
picometer | pm | |
pint | pt | |
pound | lb | |
proof | ||
psi | ||
quart | qt | |
roentgen | rontgen, röntgen | |
second | s, sec | Use for time only. |
sievert | Sv | |
tesla | T | |
torr | ||
volt | V | |
watt | W | |
weber | Wb | |
yard | yd | |
year | yr |
Combining Prefixes for SI Units
The following prefixes can be combined with SI base units to specify derived units. The derived unit or abbreviation cannot contain a space between the prefix and base unit.
Prefix | Abbreviation | Value | Example |
---|---|---|---|
peta | P | 10^{15} | 1.2 Pm |
tera | T | 10^{12} | 2.3 terajoule |
giga | G | 10^{9} | 3.4 Gg |
mega | M | 10^{6} | 4.5 megavolt |
kilo | k | 10^{3} | 5.6 km |
hecto | h | 10^{2} | 6.7 hectometer |
deca, deka | da | 10 | 7.8 dag |
deci | d | 10^{-1} | 8.9 deciliter |
centi | c | 10^{-2} | 9.0 cm |
milli | m | 10^{-3} | 0.1 milliampere |
micro | µ Note: You cannot substitute u or
mu. |
10^{-6} | 2.4 µg |
nano | n | 10^{-9} | 4.6 nanosecond |
pico | p | 10^{-12} | 6.8 ps |
femto | f | 10^{-15} | 8.0 femtometer |