Product Management interview question [Guesstimate]: How many pizzas would you need to circle the Earth at the Equator?

credits — unslpash.com

The circumference of Earth at the Equator in Kilometers is 40,075 kms, let’s take it approximately 40,000 kms.

Now, pizzas vary in sizes, where their Diameters range from 10 inches in Small segment, 12 inches in Medium segment, and 14 inches in Large segment.

Now, the number of pizzas required to circle the Earth at the Equator will depend on — The size of pizzas chosen in the scenario.

The orientation doesn’t matter in this case as the pizzas are going to be circle from whichever way.

But let’s just assume the pizzas are kept end-to-end touching each other and not any other way, somewhat like -

()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()()

where () is a pizza.

And let’s assume the size of pizzas are the usual 12 inch diameter.

Now, when we consider this scenario, the diameter of these pizzas will add up to form the length of the Equator which is 40000 kms. So,

40000 kms = 40000 * 1000 m = 40000000 m
40000000 m * 100 cms = 4000000000 cms
1 inch = 2.54 cms

So diameter of each pizza = 2.54*12 = 30.48 cms ≈ 30 cms

So the number of pizzas required to circle the Earth at the Equator = 4000000000/30 = 133333333.333 ≈ 133333333

So the number of 12 inch pizzas (kept-tip-to-tip) required to circle the Earth at the Equator is approximately 133333333.