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Hey Ray! Using Pi to Properly Buy Pizza

PITTSBURGH (KDKA) -- Remember that one time in math class when you said, "I am never going to use this in real life"?

Since tomorrow is officially Pi Day, you Know 3-14, or March 14th, we are going to use Pi to show how you may have been improperly buying pizza. Yes, math in real life!

Hey Ray
(Photo Credit: KDKA)

First, you may ask what is Pi? Many of us have learned that Pi is 3.14 and a decimal that keeps going forever.

We are going to keep it simple today and stop at 3.14. That number represents the ratio of the circumference of any circle to the diameter of that circle.

Knowing that, we can find the area of a circle by using the formula Area = πr^2.

Hey Ray
(Photo Credit: KDKA)

I would guess most people have no problem paying twice as much for a 16" pizza than an 8" since 16 is twice as much as 8.

While that may sound logical, just know that a 16" pizza has about four times more pizza in it than an 8" pizza.

Hey Ray
(Photo Credit: KDKA)

We know this because of Pi, you know that 3.14 number you learn in math class.  To find the area of a circle, you need to multiply Pi times the radius squared.

Hey Ray
(Photo Credit: KDKA)

Let's plug this into the equation.  First we need to cut the diameter of the pizza in half, since the radius is half the diameter.  On the large pizza, the diameter is 16", so the radius is 8".

That means you take Pi, or 3.14, multiply it by 8 squared, or 64.

3.14x64 is 200.96.  Meaning the area pizza is 200.96 square inches of goodness.

Hey Ray
(Photo Credit: KDKA)

Now on to the smaller, 8" pizza.

Half of the diameter is 4", so you multiply Pi or 3.14 times 4" squared, or 16.

3.14x 16 is 50.24 square inches.  That is only 1/4 the pizza area of the large pizza. How does the price per square inch break down?

We'll use rounded numbers here for easier math, but $14\200 square inches for the large pizza breaks down to $0.07 per square inch and $7\50 square inches for the small pizza is $0.14 per square inch.  This means the large is the better deal!

Hey Ray
(Photo Credit: KDKA)

Now if the pizza is square, you multiply length x width to find the pizza area.

It is a little easier than finding the area of a round pizza using Pi.

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