So how do we do more advanced mathematical operations? For example, how would we perform a square root on a number if the program doesn’t recognize a square root symbol?

There are several built-in methods that we can use to manipulate numerical data and perform more complex mathematical calculations. Here are a few:

`Math.Abs()`

—will find the absolute value of a number. Example:`Math.Abs(-5)`

returns 5.`Math.Sqrt()`

—will find the square root of a number. Example:`Math.Sqrt(16)`

returns 4.`Math.Floor()`

—will round the given double or decimal down to the nearest whole number. Example:`Math.Floor(8.65)`

returns 8.`Math.Min()`

—returns the smaller of two numbers. Example:`Math.Min(39, 12)`

returns 12.

### Instructions

**1.**

In this exercise, we’re going to use built-in methods to determine which number is smaller between the square roots of two different numbers.

First, find the square root of `numberOne`

and round the answer down so it doesn’t have a decimal. Save this value to a new `double`

variable `numberOneSqrt`

.

**2.**

Do the same process to variable `numberTwo`

and save this value to a new `double`

variable `numberTwoSqrt`

.

**3.**

Inside of a `Console.WriteLine()`

statement, use a built-in method that returns the smallest of two numbers, using the values `numberOneSqrt`

and `numberTwoSqrt`

.

Which value gets printed to the console?

**4.**

Did `NaN`

get printed to the console? `NaN`

stands for “Not a Number” in C#. So what happened?

The built-in method `Math.Sqrt()`

can only take a positive number as a value, but the value of `numberTwo`

is negative. But we can fix it. The method `Math.Abs()`

will find the absolute value of a number. A good reminder that when we use built-in methods, to check the documentation so we know how to use them!

Inside of the `Math.Sqrt()`

method, add the `Math.Abs()`

method, so it takes the variable `numberTwo`

as a value. Re-run the code and see what gets printed to the console this time!