How to Improve Your Mental Math for the Management Consulting Application

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There are some critical skills that you need in order to get a consulting job. Having strong mental skill is definitely one of them. However, this skill seems to be the first to go once pressure kicks in.

You definitely need excellent analytical and problem solving skills, but mental math is an important element of a consultant’s essential skills set. Having this skill will help you compute for quantitative data such as graph analytics, cost reduction, general averages, etc. Although you may not need to always provide the exact figure, mental math can definitely help you get as close to the exact answer as possible within a limited amount of time, without the aid of calculator.


Mental math plays a significant role in the consulting world as such skill helps consultants develop a structured way of thinking. As a result, it can help keep your mind sharp and active as well as boost your concentration levels. And ultimately, having strong mental math skills can increase your confidence in solving cases that demand critical quantitative analysis.

Mental Math & the Recruitment Process

Strong quantitative skills are indispensable in the consulting recruitment process, particularly during case interviews. It is really important that you can crunch numbers very well to prove that you have what it takes to be a consultant. And of course doing mental math in a regular day is very different from doing it for an exam in a short amount of time. As an aspiring consultant you need to understand that during the case interviews, recruiters want to see how you will apply frameworks to solve the sample case. Proper mental math skills will definitely help you crack the case. Avoid being caught off-guard and hone your mental math.

How to Hone Your Mental Math

There are basic tips and tricks that can help sharpen your quantitative prowess. Some of which are:

Mastering the Foundation

Are you confident with basic math equations? Well, you better master them as this is your foundation to having strong mental math skills. Make sure you are pretty comfortable with the four basic operations – adding, subtracting, multiplying and dividing. And not just with whole numbers but with fractions, percentages and averages as well.

So try to solve as many sums, differences, products and quotients in your head as you can. Dedicate specific times a day, for instance an hour, to practice your, summation, division, multiplications, etc. This will really help you increase your speed.

Don’t Stop at Single and Double Digits

As you practice basic math operations, aim to get comfortable even with 3-4 digits. As the numbers get more complicated, it will be harder to compute for the exact figure. This is where you need your estimation skills.

Practice Estimation

As you try to solve for bigger numbers, round off numbers so you can easily arrive at an estimated answer. Again, practice this until you are pretty confident that you can handle any kind of number data during the consulting interview.

Do Mental Math in Your Everyday Life

If you develop a habit of using mental math to calculate the sum your grocery bill, estimated overhead, service and food costs at a restaurant, electric bills and credit card statements and so forth, you’ll get used to it pretty fast. Get your mental math muscle to work as hard as possible. This will ensure you won’t get shocked on your interview day. Remember that in a consulting setting, you won’t be counting apples and oranges. So it is best to apply your mental math skills in real-time problems.

Research for Pre-worked Out Shortcuts

Be aware that some numbers have ideal properties, and you can take advantage of the available pre-worked out shortcuts to find the solution. For instance, when multiplying 2-digit numbers by 11, say 23 x 11, just sum the digits (2 + 3 = 5) and put it between the 2 and 3 to get the answer: 253. Amazing, right?

The same trick is applicable for 3-digit numbers, say 523 x 11 (5+2 = 7, 2 + 3 = 5). Then stick them between 5 and 3 to get 5753.

This is just one of the many pre-worked out shortcuts you can use. Research for more shortcuts and practice using them as well. Of course, part of the challenge is being able to know when you can use a specific technique.

Structured Practice Techniques

There are many sources available online that go into detail about key mental math techniques such as Trachtenberg, High Speed Vedic Mathematics, Kumon Math Method and many more. You may also want to read some books Chinese that elaborate different mental math systems, like The Nine Chapters on the Mathematical Art. Of course you have to determine which ones would work best for you. If you are not comfortable with a certain technique, don’t force yourself to learn it as this would not be beneficial for you in the long run.

Try to Enjoy Puzzles and Mental Teasers

Puzzles and other types of brain teasers can further strengthen your mental math muscle. For instance, try to complete two or three Sudoku puzzles every week. Such puzzles provide better mental math challenges. As you get used to these teasers, vary the level of difficulty to really hone your numeric skills.

Test Your Speed and Accuracy

After some time and you feel that you are pretty much ready for the consulting interview, have somebody create a written test for you that consists of about 50 different real-life problems involving numeric computations. This will help you gauge how much you’ve learned and to spot in which areas you’d still need to improve.

Lastly, try to enjoy the process. Everything will be much easier if you are having fun!

Learn More

Ready for the real challenge of the consulting world? Learn more about what it takes to land your dream consulting job. Download our free guide, Learn How to Break into Consulting, and be fully equipped with the right knowledge, materials and skills to ace the consulting recruitment process.

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