# What are the basic prefixes used in the metric system, and what do they mean?

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### 3 Answers

These are prefixes commonly used in the metric system for quantities that are very small:

centi- is one-hudredth. For example, 5 cm (centimeters) equals 0.05 meters.

Milli- is one-thousandth. For example, 5 milligrams equals 0.005 gram.

Micro- is one-millionth. For example, 5 `muA` (microAmperes) is 0.000005 Amperes. This is a unit in which electric current is measured.

Nano- is one-billions. For example, 5 ns (nanoseconds) equals 0.000000005 seconds.

Occasionally you might also see such prefixes as pico- (`10^(-12))`

and fempto- (`10^(-15)).`

The following are the prefixes that are commonly used in the metric system for quantities that are very large:

kilo- is thousand. For example, 5 kg (kilogram) equals 5,000 gram.

Mega- is million. For example, 5 MW (megawatts) is 5,000,000 Watts. This is a unit in which electric power is measured.

Giga- is billion. For example, 5 gigabytes is 5,000,000,000 bytes. Even though I am not sure if the units for measuring data officially belong to the metric system, the prefix is still the same.

Occasionally you might also see such prefixes as tera-, `10^12`

and peta-, `10^15.`

Commonly used metric prefixes for **large quantities** are :

Deca Symbol da means Ten `10^1`

Hecto Symbol h means Hundred `10^2`

Kilo Symbol K means Thousand `10^3`

Mega Symbol M means Million `10^6`

Giga Symbol G means Billion `10^9`

Tera Symbol T means Trillion `10^12`

Peta Symbol P means Quadrillion `10^15`

Commonly used metric prefixes for **small quantities** are :

deci Symbol d means one-tenth `10^-1`

centi Symbol c means one-hundredth `10^-2`

milli Symbol m means one-thousandth `10^-3`

micro Symbol `mu` means one-millionth `10^-6`

nano Symbol n means one-billionth `10^-9`

pico Symbol p means one-trillionth `10^-12`

femto Symbol f means one-quadrillionth `10^-15`

**Sources:**

A metric prefix is a modifier on the root word and it tells us the unit of measure. For example, centigram means we are count in steps of one one-hundredth of a gram, μg means we count by millionths of a gram.