## Functions

# Built-in Functions

A built-in function is one that you don’t need to install and load a package to
use. To learn how to use a function you can use the `help()`

function or the
`Help`

tab in RStudio. `help()`

takes one parameter, the name of the function
that you want information about (*e.g.,* `help(abs)`

) or type the name into the
search box on the `Help`

tab. Familiarize yourself with the built-in functions
`abs()`

, `round()`

, `sqrt()`

, `tolower()`

, and `toupper()`

. Use these built-in
functions to print the following items:

- The absolute value of -15.5.
- 4.483847 rounded to one decimal place.
*The function *`round()`

takes two
arguments, the number to be rounded and the number of decimal places.
- 3.8 rounded to the nearest integer.
*You don’t have to specify the number of
decimal places in this case if you don’t want to, because *`round()`

will
default to using `0`

if the second argument is not provided. Look at
`help(round)`

or `?round`

to see how this is indicated.
`"species"`

in all capital letters.
`"SPECIES"`

in all lower case letters.
- Assign the value of the square root of 2.6 to a variable. Then round the
variable you’ve created to 2 decimal places and assign it to another
variable. Print out the rounded value.

*Challenge*: Do the same thing as task 6 (*immediately above*), but instead of
creating the intermediate variable, perform both the square root and the round
on a single line by putting the `sqrt()`

call inside the `round()`

call.

[click here for output]