# Hey Ray! Shopping for Pizza Proper With Pi – CBS Pittsburgh

PITTSBURGH (KDKA) – Do you remember saying in math class, “I’ll never use this in real life”?

Since tomorrow is officially Pi Day, you know, 3-14 or March 14, we’re going to be using Pi to show how you may have wrongly bought pizza. Yes, math in real life!

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At first you might be wondering what is pi. Many of us have learned that pi is 3.14 and a decimal place that goes on forever.

We’re going to keep it simple today and stop at 3.14. This number indicates the ratio of the circumference of a circle to the diameter of that circle.

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

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

While this may sound logical, just know that a 16-inch pizza contains about four times more pizza than an 8-inch pizza.

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 by the square of the radius.

Let’s put that into the equation. First we need to cut the diameter of the pizza in half as the radius is half the diameter. The large pizza has a diameter of 16 inches and a radius of 8 inches.

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That is, you take pi or 3.14 and multiply it by 8 square or 64.

3.14 × 64 is 200.96. That is, the pizza area is 200.96 square inches of goodness.

Now for the smaller 8-inch pizza.

Half the diameter is 4 “so multiply pi or 3.14 times 4” squared or 16.

3.14 x 16 is 50.24 square inches. That is only 1/4 the pizza area of the big pizza. How is the price distributed per square inch?

We’re going to use rounded numbers here to make the calculation easier, but 14-200 square inches for the large pizza is $ 0.07 per square inch and 7 to 50 square inches for the small pizza is $ 0.14 per square inch. This means that the big is the better deal!

If the pizza is square, multiply length x width to find the pizza area.

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It’s a little easier than using Pi to find the area of a round pizza.

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