Five Steps to Improve Your Mental Math

Written by . Posted in Case Interview Prep, Consulting Application

old wooden abacus on background working papers

Mental calculation is an indispensable task in management consulting. Even during case interviews, it’s evident that prestigious firms such as McKinsey, Bain, and BCG look for candidates who are number smart—who can analyze and interpret quantitative information without relying solely on a calculator.

Why Improve Your Mental Math

Like most management consulting aspirants, you probably want to enhance your mental math merely for the purpose of acing the interview and creating a positive impression on the recruiter. Perhaps you’re not aware that improving your mental math will enhance additional competencies necessary to a management consulting position:

  • It improves your level of concentration.
  • It enhances your discipline, determination, and endurance.
  • It sharpens your memory and observation.
  • It trains your mind to be active and think logically.
  • It lets you explore options, not just stick to one possibility.
  • It prepares you for analysis and problem-solving.

The skills listed above will help you sail through not only the case interview but also the management consulting lifestyle itself. Working on your quantitative intelligence will help you land a job and advance  your career.

How to Improve Your Mental Math

You can use the following activities to improve your mental math:

Step 1: Master Basic Math Operations

It’s impossible to learn advanced mental math techniques if you’re not skilled in the basic operations, percentages, fractions, and ratios. Start by adding, subtracting, multiplying, and dividing two or three-digit numbers. Then proceed with squaring numbers and using the art of guesstimation. In the long run, you’ll be surprised to instantly figure that 70,154 is a multiple of 7.

Step 2: Practice Interpreting Charts and Tables

For management consultants, mastering basic math operations is useless if not applied in actual scenarios. Grab a chart or a table, analyze the figures, do quick mental calculations as needed, and come up with a sound interpretation. Understand the labels, value scales, intervals, and other stated information in order to make connections and determine which figures to add or multiply. Make sensible estimates if applicable. For instance, from a bar graph that shows the income of a comic shop from 2000 to 2010, you can easily predict the possible income in three years’ time from the bar patterns.

Step 3: Learn Math in Different Ways

There are a variety of ways to learn and/or master mental math. You can read books that teach you several tricks to speed up your computations and provide drills for practice. Another way is reading resources and watching free or paid videos on the Internet. Mobile apps that aim to improve your calculations are also available. A popular example is Mathemagics, an app originally developed for math test examinees and challengers who desire to quickly reach more accurate solutions.

Step 4: Play Puzzles and Brain Teasers


Learning math through challenging games is always exciting. You relieve yourself from the pressure of getting correct answers because fun takes the front seat. Sudoku, a grid popularized by a Japanese company, is an excellent exercise for improving your concentration while engaging with numbers. Brain teasers, logic puzzles, riddles, and other mind benders also enhance your numerical and logical skills.

Step 5: Compute Anytime, Anywhere

Numbers are everywhere. There is math involved in the huge building where you attended a social event or in the blue thumbtack you used in posting a note. When you have idle time, you can simply choose to be mindful of the numbers surrounding you. While in a long queue at a supermarket, observe and estimate how many customers a cashier processes in a day. While waiting for a friend at a bookstore, add up the number of pages there are in a stall.

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