# Built-in Functions (Functions)

A built-in function is one that you don’t need to install and load a package to use. Some examples include:

• `abs()` returns the absolute value of a number (e.g., `abs(-2`))
• `round()`, rounds a number (the first argument) to a given number of decimal places (the second argument) (e.g., `round(12.1123, 2)`)
• `sqrt()`, takes the square root of a number (e.g., `sqrt(4)`)
• `tolower()`, makes a string all lower case (e.g., `tolower("HELLO")`)
• `toupper()`, makes a string all upper case (e.g., `toupper("hello")`)

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

1. The absolute value of -15.5.
2. 4.483847 rounded to one decimal place.
3. 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.
4. `"species"` in all capital letters.
5. `"SPECIES"` in all lower case letters.
6. 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.

Optional 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.

Expected outputs for Built-in Functions: 1