Driving to Pizza House: A Mathematical Tale

Last year we started taking Jana out to dinner to celebrate Epiphany. This year Jana wanted to go to the Clyde Pizza House. Clyde is about 12 miles away from Abilene, but we think the Clyde Pizza House has some of the best pizza we've ever had. Plus, on weekends they often have local bands playing live, old school (very old school) country music.

Anyway, last week on the drive out to Clyde Jana and I had the following conversation. It's a story for all you math teachers out there:

Me: "Do you want to call ahead and get the pizza ordered?" (We often do this so we don't have to wait long for the pizza when we get there.)

Jana: "I'm not sure. The boys are eating a lot more so we need to order more pizza. I want to look at the sizes to see what we should order."

"You know what we should do? We should find out the area of the large pizza we get and then order an additional half of that. Because a large and a half would work, right?"

"Yes, that's about the amount we need."

"So all we need to do is find the area of the large pizza and then find the areas of the smaller pizzas to see which one comes closest to half the area of the large."


"So what's the formula to find the area of a circle?"

"I don't know."

"Me neither. Look it up on your iPad."

(Jana looks and reports back) "It's A = πr2

"r is the radius, half the diameter, right?"


"So let's call and get the diameters of the pizzas they have."

(Jana calls Pizza House and reports back) "They have a 16'', the one we get, plus a 14'', 12" and 9"."

"Okay. Let's find the area for the 16''. That would be A = 3 (let's round to make this easy) x 82. What does that equal?"


"Okay, so a large is close to 200 square inches of pizza. So all we need to do is to find a smaller size that is about half that size, something close to 100 inches."

"Well, the next size is 14". That would give us A = 3 x 72. That's...147."

"Too much."

"Too much."

"Try the next size, the 12"."

"For the 12" we have A = 3 x 62."

"That's 108."

"That's close to 100, just what we need."

"Right. Call it in."

(Jana dials) "Yes, we'd like to order one 16" pizza and one 12" pizza..."
And you know what? It was the perfect amount.

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12 thoughts on “Driving to Pizza House: A Mathematical Tale”

  1. Hooray for applied mathematics!

    Incidentally, in a basic math class that I've taught several times, I've often asked students to pick between one 16-inch pizza or two 10-inch pizzas. Most incorrectly pick the second option, apparently believing they're getting the same area as a 20-inch pizza.

    Of course, if they're only in it for the pizza crust (i.e. circumference), then their choice makes sense.

  2. I love the story. It reminded me of a story in a parenting book I really enjoyed "Raising Self-Reliant Children in s Self-Indulgent World." The author told of the time he and his son were on a tractor and had to use some math to figure out some issues mowing down stumps. At one point in the course of their dialogue the boy asked his dad, "Does this have something to do with math?"

  3. So here's one for you next time:

    Figure out whether it's quicker to go to the Clyde pizza house from my house going on I-20 or on hwy 18 (the "back" way). On one you can travel 70 mph for 15 minutes but it takes a while to get to the interstate. On the other, you have more starts and stops but it's right by our house.

    Now: let's save our $ and take our wives back to Clyde, only this time to Bonterra Blu. http://www.bonterrablu.com/Bonterra_Blu/Home.html. (We haven't been yet.)

  4. Having hit it off with a funny, bright, energetic young woman, I asked her on a date. She said her dad liked to meet her dates, so our first time out was to a pizza place with her parents. I didn't know in advance that her dad was the local Air Force base commander. My first interaction with the colonel was about which pizza size was the best value. FAIL. (There were no iPads in the olden days.) But I learned a cool approach to meeting my future kids' dates.

  5. Hmmm....We have five adult children, 3 of whom are men. We have bought quite a bit of pizza in the last couple of decades, and I was completely unaware that it is possible to buy too much.

  6. I too have experienced pizza house on concert night and it's fun stuff. Clyde has about 15 people in the whole town strewn along I-20, and all the ones with a heartbeat, and perhaps some without, are eating pizza (really, really good, by the way) and tapping there toes to songs I barely recognize with full country instrumentation (including banjos and a harmonica). Thanks for the flashback!

  7. This is late, but OK. I'll bite. The best pizza I ever had was at Milano's in Heidelberg, Germany. Size did not matter.


  8. I always get pizza every lunch and I'm enjoying it. Anywhere around you can search for a good food with different specialty of taste and you will get used to it. Happy eating everyone :)


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