Whether you majored in English or Mathematics, consulting firms will expect candidates to have a certain level of proficiency in math. The good news is that the math in case interviews isn’t terribly difficult. You don’t have to worry about anything beyond arithmetic. However, under time pressured situations like those in case interviews, performance can suffer. Sometimes what you thought you knew goes out the window when under pressure. The best way to prepare is by practicing math drills.
You can peruse the case interview math tips below, or you can listen to Jenny Rae, ex-Bain consultant in the video below. She talks about how to prepare for case interview math through the use of math drills. But even more than just using math drills, it’s making sure that you arrive at the business insight that’s most important for case math.
What Are Math Drills?
Math drills are short math timed tests that help improve their accuracy and speed. Usually a math drill is on a particular topic, such as addition or division. However, it’s possible to create math drills with a mixture of topics. They are usually timed, or if they aren’t, the goal is to complete these math speed drills quickly and accurately.
The Importance of Practicing Math Drills
Research shows that frequent, short periods of practice is an effective method of retaining math facts. Though some people are born with a knack for math, just like most other things in life, math is something that can be learned and improved upon with practice. Treat math like you would muscles that you are building at the gym – with enough repetitions and sets, your math muscles can become stronger and formidable. Through math drills, all the extra math you do on different topics will help you build your skills and confidence, both of which are required for successful performance in case interviews.
As discussed, the math itself isn’t hard in case interviews. However, with the pressure of an interviewer looking at you, the complexities of the other parts of the case, and limited time, fast math can be a challenge. Especially if math isn’t your strong suit! Practicing math drills like multiplication drills and addition timed tests is essential before you step into a case interview.
How Fast Do You Need To Be?
You’ll need to be able calculate most of your math within roughly 5-10 seconds. Let’s use an example, try to calculate:
150 million ÷ 20 x 25%
How long did that take you?
If it took you longer than 10 seconds, then it means that you’ll definitely need more practice. Five seconds is even better to shoot for. If that sounds impossible, don’t worry, it just means you don’t yet know the tips and tricks you need for fast math.
Using Math Drills Effectively
There are several different approaches in using math drills effectively. 
In order to make best use of your time, we suggest adhering to the following tips:
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Gradually Increase Level Of Difficulty
Math drills differ in level of difficulty. Most resources allow you to change the level of difficulty across the various types of math that you are practicing. Depending on your skill level, start with the easier math drills first; starting with the more difficult drills may lower your confidence and won’t be an effective use of time. Get the fundamentals down before anything else!
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Practice On A Consistent Basis
You don’t need to start practicing with your math drills if your case interviews are a year away. However, if your recruiting season is coming up within the next few months, we recommend starting practicing your math skills. Set a scheduled time and gradually increase your repetitions as your interviews come closer. Above all, make sure to practice on a consistent basis – you’ll be surprised how quickly your math skills may fade if you don’t.
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Focus On Math That Is Difficult For You
We see a lot of people come through, they get into math drills, and they enjoy them as a confidence-building exercise. And there’s something to be said for confidence but not when you’re headed into the case interview. Math drills are really important for building the core skills that you’ll need when you’re under pressure, on the spot, and the things that you’re most likely to fall down on, are not the ones that you know cold, but the ones that are the weaker areas for you. So, when you’re thinking about math, math drills, and mental math, focus on your weak areas.
We realize sometimes in life, it’s important to play to your strengths. However, in case interviews, you can’t control the type of math that you’ll be asked to perform. That’s why we recommend starting with the math that you are weakest at and use math drills to turn them into a strength. That doesn’t mean to start with the hardest drills, (see tip 1 above), just start with the area of math that you struggle with most. Within that area, start easy and allow yourself to grow confidence.
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Drill Math In The Way That You Would Need To Use It Inside The Case Interview
You need to drill math in the way that you would need to use it inside the case interview. Therefore, you need to actually talk through math drills out loud, not just focus on computing them in your head and definitely not using cheat areas like calculators. So your focus needs to be on replicating the environment that you’re gonna use the math drills in. This would also be true if you use the same math drills to practice for a GMAT or a GRE or an SAT. When you’re practicing the math drills, doing it in a test simulated or an interview simulated environment, it’s gonna be the most important thing.
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Focus On Accuracy
Finally, you really need to make sure that you’re getting the mechanics down that focus on accuracy. So you need to use math drills that give you immediate feedback on accuracy, and redo areas where you have under a 90% accuracy. Why is that important? Well, if you have only 10% that is inaccurate, it’s going to be easier to catch when you’re going through an interview, if you make a mistake. You’ll quickly recognize the 1 out of 10 times that you compute something wrong. But if you have a larger area of inaccuracy, then you’re gonna result in situations where you actually don’t know what you’re doing. It’s also going to affect your confidence when you’re working through the case.
Conclusion + Bonus
So overall these tips, if you get them right, you’re gonna maximize the drills effectiveness. Now, from our perspective, we think it’s incredibly important to give you opportunities to drill as many math drills as you want. But I would say another bonus or, “asterisk” area, is if you can give yourself a benchmark against other people. Accuracy, that’s pretty easy to identify. Did you get it right or wrong? But speed, you won’t necessarily know if you’re fast enough, unless you benchmark yourself against other people or work directly with a coach.
At Management Consulted, we don’t believe in being lightning fast in math, because that’s not the goal. 100 percent or at the minimum 90% accurate and “speedy enough”, is the goal. By the way, which is usually in under 10 seconds, computing each step of the math. So if you need barometers for that, use our math drills. We have free ones and paid ones. And it would be awesome to support you in your journey to get better at mental math, using math drills for the case interview. We’re here to help!