Posted by: Kash Farooq | July 29, 2015

Domino’s Pizza and the Area of a Circle

My excuse for this post: I’m between Open University modules at the moment and have spare time on my hands.

Make nice pizzas, but don't do maths.

Make nice pizzas, but don’t do maths.

We’ve just had our (seemingly monthly) Domino’s pizza menu through the door. The prices between the different sizes seemed odd so I created a spreadsheet…

The bog standard Cheese and Tomato:

Type Diameter (inches) Price Area (square inches) Price (pence) per square inch
Personal 7 £3.99 38.48451 0.1037
Small 9.5 £8.99 70.8821842 0.1268
Medium 11.5 £10.99 103.868907 0.1058
Large 13.5 £12.99 143.138815 0.0908

 
The small pizza works out much more expensive than the others.

The “mid-range” pizzas

Type Diameter (inches) Price Area (square inches) Price (pence) per square inch
Personal 7 £5.99 38.48451 0.1556
Small 9.5 £12.99 70.8821842 0.1833
Medium 11.5 £14.99 103.868907 0.1443
Large 13.5 £16.99 143.138815 0.1187

 
Whoa! Don’t get a small pizza! Compared to a small pizza, two “personal” pizzas will be cheaper per square inch, will give you more square inches in total (76 vs. 71) and will cost you £11.98 instead of £12.99.

The “high-end” pizzas

Type Diameter (inches) Price Area (square inches) Price (pence) per square inch
Personal 7 £6.99 38.48451 0.1816
Small 9.5 £13.99 70.8821842 0.1974
Medium 11.5 £15.99 103.868907 0.1539
Large 13.5 £17.99 143.138815 0.1257

 
Same again. Small pizzas are the most expensive. Two personal pizzas will give you more pizza in total, and costs the same as one small pizza.

 

The moral of the story: don’t buy small pizzas from Domino’s.

 


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