Interview Questions

Interview Maths Is Your Secret Weapon

Interview maths isn't the same maths you come across in online tests, this is the maths you begin learning at an even younger age, addition, subtraction, multiplication and division with the occasional percentage thrown in for good measure. They become difficult because you are working under pressure with big numbers such as multiplying 70,000 by the 356 days of the year. It is extremely easy to miss a 0 or get yourself into a mess when you don't have a calculator!

Sitting outside interview rooms at assessment days talking with other candidates, one of the most common comments is along the lines of "Oh my god, I had a complete brain freeze with the maths". If practiced, it isn't difficult to perform the maths part of interviews quickly and competently. Demonstrating good maths skills can be your differentiator as it is so often where mistakes are made and fellow applicants stumble. 

It is particularly useful in market sizing/guesstimate questions as well as consulting case studies. This is because you are often talking about market sizes or populations and want to only consider subsets of these large numbers.


For example, you may be working through a consulting case study and be told that a manufacturer of hairbrushes has fixed costs of £3,000,000 and they sell 175,000 units a year, what is the fixed cost per unit?

The example above was a question used by a tier 2 consulting firm in 2018 and a good candidate will be able to tell you that its approximately £17.1 within 30 seconds. Being quick is not only a major plus for your performance but it also helps keep a natural flow to your interview, helping you build rapport with your interviewer.

However, it is important to remember that the interviewer is unlikely to be  directly testing your maths skills and therefore, if you have the choice, make the numbers easy for yourself. As an example it is always helpful to take the UK population as 60 million rather than its true value of 66 million. They aren't always looking for perfect answers, just a good thought process and ball park figure.

It is also possible that a calculation isn't required at all and and if you are in doubt then explain out loud the calculation you are about to make and the interviewer may agree it is a good thing to do, they may give you the answer or they could course correct and push you to a different part of the problem. It is important to give the interviewer the opportunity to help you as much as possible.

We have 25 arithmetic questions available to download for you to practise with. Unlike online tests there is less of a time pressure element involved with this maths and you should instead focus on rehearsing your technique and getting the correct answer.

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