# Use Math.PI To Calculate Area And Circumference Of A Circle

### Introduction

The `Math.PI`

property returns the PI `π`

constant, approximately equal to 3.14159. For example, you can calculate the circumference and surface area of a circle using `Math.PI`

.

`console.log(Math.PI); // 3.141592653589793`

## Calculating Circumference Of A Circle

Write a function that accepts a `number`

as the circle's radius as the following example:

`function circleCircumference(radius) { return 2 * Math.PI * radius; } console.log(circleCircumference(16)); // 100.53096491487338`

## Calculating Area Of A Circle

Like the previous example, write a function to calculate the surface area:

`function circleArea(radius) { return Math.PI * (radius * radius); } console.log(circleArea(16)); // 804.247719318987`

You can re-write the above function by using the `Math.pow()`

to calculate the `radius^2`

:

`function circleArea(radius) { return Math.PI * Math.pow(radius, 2); } console.log(circleArea(16)); // 804.247719318987`

Also read about the Math.ceil() function and Math.floor() function.