Practice Your Math Skills Everywhere

Written by . Posted in Case Interview Prep, Tests


Sitting in a coffee shop now and just had a discussion with a friend about how people best can utilize their time when preparing for interviews. It hit me just how much we all can actually use our everyday situations to our advantage. Especially a thing like practicing math skills, which is essential for consulting. Read more…

You might think that this is not necessary in a world of spreadsheets and calculators. I have two points about this: firstly, the interview process itself is very demanding about your math skills. Secondly, great math skills are very useful in the day-to-day management consulting job afterwards.

There are many situations where this is true. Even in the most simple meetings, numbers are thrown up in the air: “What would our margin be?”, “How much did the 10% discount cost the client last year?”, or the cliché “What is the quick and dirty estimate of the market?”. At client meetings you might also get questions where math skills will help you a lot.

Estimation Example

Use all situations in your everyday life to your advantage. Take my coffee shop location now. I could try to estimate the daily revenue of this coffee shop. Here are the steps that I would go through.

How many customers do come here during daytime?

There are 20 seats, and it is afternoon now – the busiest part of the day. About 15 seats are taken. I will assume that 10 seats are occupied at any time, and that the average length of visit is 1 hour. So there are 10 seated customers per hour. The coffee shop is open from 8 am to 10 pm – this is 14 hours. So, there are 140 seated customers per day.

Apart from the seated customers, there are also some people buying takeaway coffee as the coffee shop is located close to some office locations. My guess is that there are about twice as many takeaway customers – so 280 per day.

What is the average spend per customer?

The seated customers usually buy coffee (about EUR 3) and some snacks or a cake (about EUR 1). A total of EUR 4. The takeaway customers usually only buy coffee, so lets assume the average revenue for them is EUR 3 per customer.

What is the daily revenue?

  • For seated customers: EUR 4 * 140 customers = EUR 560
  • For take-away customers: EUR 3 * 280 customers = EUR 840
  • Total: EUR 1.400

Other Examples

Here are some other useful situations where you can practice your mental math skills:

  • in grocery stores, try to calculate the total price of all items you put in your basket (including possible discounts!)
  • estimate daily/monthly/annual revenue of different stores, bars, cabs, hairstylists, etc. where you are present
  • when you wait for your food at a restaurant, estimate the total costs of different ingredients

Estimating annual revenue for a cab driver might sound silly – but the process is the same as for estimation cases, and you will quickly get up to speed with your math skills if you push yourself. Ask yourself what you can do NOW to practice your math skills.

Have a look at our guide on How to Land a Job in Management Consulting which has more advice for consulting interview preparations.