I was chatting with Jessica the other day and she mentioned how she was blindsided with a really strange interview question that went like this:
How many golf balls are sold in Canada?
Sounds TOTALLY random right?
Well it’s not.
It’s actually something that gung-ho business school-type interviewers use to screen candidates to test for logic, basic math skills and how fast you can think on the fly.
The way to answer it (as I was taught in school) is to keep these things in mind:
- Keep the math simple
- Use the (few) facts you have on hand
- Talk out loud as you are reasoning through the problem
KEEP THE MATH SIMPLE
Use 10s or 100s. Don’t try and get fancy with 75 or any odd numbers that are hard to multiply, add or subtract. You need to keep this simple so that you don’t need a calculator under such pressure.
USE THE ACTUAL FACTS YOU HAVE ON HAND
You don’t need many, just one is enough.
For example, you know there are:
- 10 provinces in Canada
- 3 territories
We can safely assume that no one golfs in the Territories, so just concentrate on the provinces as your number.
TALK OUT LOUD AS YOU ARE REASONING THROUGH THE PROBLEM
Talk as you are writing down the calculations.
In the above example, you already know that there are 10 provinces in Canada, so now you can make up a few facts or logical assumptions.
Something like this:
- There are golf courses in Canada (guess at this number, say 10 or something because there is on average ONE in each province)
- There are people who golf abroad who also buy golf balls, let’s say 10,000 in each province on average.
Then you make up some guesstimate numbers:
GOLF COURSES THAT BUY GOLF BALLS:
10 golf courses could buy 500,000 golf balls each year on average
500,000 x 10 = 5,000,000 golf balls
PEOPLE WHO GOLF AND BUY GOLF BALLS:
10,000 people x 10 provinces = 100,000 people in total
100,000 people x 100 golf balls a year = 10,000,000 golf balls
TOTAL GOLF BALLS SOLD IN CANADA
Now add the two numbers together:
5,000,000 + 10,000,000 = 15,000,000 golf balls sold in Canada each year
That’s how you solve a case study interview question.