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4.9 Formatting SI Units

If you need to typeset numbers and units then I strongly recommend
that you use the `siunitx` package. This section just provides
a brief introduction to that package. You will need to read the
`siunitx` package documentation [20] if you want
further details.

This command typesets *<number>*, adding appropriate spacing between
number groups where necessary. It also adds a leading zero if
omitted before the decimal point and identifies exponents. Note that
the command recognises both “`.`” and “`,`” as the
decimal marker. If you want one of these characters between number
groups (instead of the default space) you can change the settings,
but it's best to stick to the default settings unless instructed to
do otherwise.

**Example:**

`\num`

`{12890}`experiments,

`\num`

`{1289}`of them had a mean squared error of

`\num`

`{.346}`and

`\num`

`{128}`of them had a mean squared error of

`\num`

`{1.23e-6}`.

Result:

This command typesets an angle. The argument *<angle>* may be a
single number or three (some possibly empty) values separated by
semi-colons.

**Example:**

Result:

This command typesets a unit. The *<unit>* can be formed from
commands like `\metre`

, `\gram`

, `\second`

or `\kilo`

.
(See the `siunitx` documentation [20] for the full
list.)

**Example:**

`\si`

`{`and the area in

`\kilo`

`\metre`

}`\si`

`{`. The acceleration was given in

`\kilo`

`\metre`

`\squared`

}`\si`

`{`.

`\metre`

`\per`

`\square`

`\second`

}Result:

This combines the functionality of `\num`

and `\si`

so
that you can typeset both a number and a unit.

**Example:**

Result:

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