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 1015 1.2 Pm
tera T 1012 2.3 terajoule
giga G 109 3.4 Gg
mega M 106 4.5 megavolt
kilo k 103 5.6 km
hecto h 102 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