# How to Use Pi to Calculate Volume of a Sphere

## How to Use Pi to Find the Volume of a Ball or Sphere

Are you trying to figure out the volume of a sphere? You know you need to use Pi, and you know there's a formula for the volume of a sphere, but you need a little assistance. Let me help! Using Pi to calculate the volume of a sphere is pretty straightforward. These simple steps help you to use pi to find the volume of a ball or sphere of any size.

## What Is Pi and How Do You Use It?

First, recall that Pi is a number that is used to figure out all kinds of information about circles, spheres, and cylinders. Pi is usually expressed as the decimal number 3.1415... meaning it never stops. It also never repeats! This fact has driven mathematicians insane (literally! Ever see "A Beautiful Mind?" ). Since it never actually ends, you are usually allowed to use a shortened version, like 3.14. If your teacher insists, you may have to use the Pi button on your calculator -- but never fear! just substitute it for 3.14 and you're good to go.

By the way, there are lots of on-line "math help" and tutor sites that can help you with this or any other of these concepts and steps. One good one for free math worksheets is right here.

## This is a sphere (the ball, not the boy's head)

## What Is a Sphere?

Of course, you do need to know what a sphere is. A sphere is simply the official name for a ball -- the Earth, a tennis ball, and a round balloon are all examples of spheres. they are all the same in shape, but not in size -- this is a key point, and it's the reason we need Pi. No matter what size your sphere is, Pi will work in an equation to find its properties -- volume, area, diameter, radius, and so on.

## Let's Find the Volume!

We'll assume you know the radius of your sphere -- it's exactly half the diameter. You'll most likely be given this in the typical math problem asking for volume of a sphere with a radius of 8 inches. For example, if the diameter is 16 inches, the radius is 8 inches.

Now let's use the formula to use pi to find the volume of a ball or sphere with a radius of 8 inches. Here's the formula:

**4/3 x Pi x radius cubed.**

**Let's break that down a little!**

For this exercise, we will convert 4/3 to its decimal form: 1.33. That gives you this formula:

**1.33 x Pi x radius cubed**

Break it down a little more by substituting 3.14 for Pi, and we get this:

**1.33 x 3.14 x radius cubed**

Pop in our value for the radius, which if I remember correctly is 8 inches:

**1.33 x 3.14 x 8 cubed (8x8x8)**

**That gives us our kind-of final product: ****1.33 x 3.14 x 672**

Now it's really just a matter of getting out the calculator and doing the math. When I did it, this is what I got:

**1.33 x 3.14 x 672 = 2,806.4064 cubic inches **

**DONE!**

## Woof woof! I like writing for HubPages!

I actually do... And you might, too. There's a little money in it, and it's the perfect way to spend your free time productively. CLICK HERE to check it out.

## More by this Author

- 6
Identify basement bugs with this authoritative and well-researched guide. You might be surprised to find out which bugs are actually helpful, and which bugs constitute a real emergency!

- 9
This photo-rich article illustrates some of the more commonly found caterpillars in North America.

- 10
Hornworm caterpillars eat the leaves and fruit of tomato plants in your garden. Here's how to identify them and keep them from eating all of your tomato harvest.

## Comments

No comments yet.