Mental Math for Quantitative Traders
How to prepare for the mental math portion of quantitative trader interviews.
Why study mental math?
One of the core competencies that is evaluated during quantitative trader interviews is a candidate's numerical skills. More often than not, this skill is tested through a series of mental math games and challenges. During these games, you will be presented with a series of arithmetic questions ranging from integers to decimals and fractions. Your objective is to answer as many questions as you can within the restricted time limit. Here is an example of a few variants of questions you may be asked:
- ? × 4.5 = 31.5
- 14 × 8 = ?
- 145 ÷ ? = 29
The precise format of the mental math test can vary from company to company. Here are a few examples of mental math tests from various companies.
Optiver gives an 80 in 8 test in which you have 8 minutes to answer 80 multiple-choice questions that are presented in sequential order. Each incorrect answer results in a 2-point deduction, and each correct answer is worth 1 point.
Akuna Capital administers a similar exam to Optiver's. You are given 80 multiple choice questions to solve in 8 minutes, except the point deduction for an incorrect answer is 1 point.
Flow Traders has a different format for their exam. Flow's exam is divided into three distinct sections. The first section covers integer questions, the second covers decimal questions, and the third is a multiple choice multiplication section.
The IMC Trading exam consists of 24 math, reasoning, and pattern questions that you must solve in 18 minutes. For the reasoning/pattern questions, you are given a series of numbers and are asked to predict what the next number in the sequence will be.
If you have an upcoming interview with a firm that assesses mental math, it is important to practice these types of questions well-ahead of your assessment. Even for the most astute mathematicians, solving random arithmetic questions under a restrictive time constraint can be challenging without practice. In this article, we'll share a handful of resources and techniques you can employ in order to successfully pass this stage of the interview process.
How to prepare for trader mental math?
Unfortunately, there aren't any shortcuts to getting good at mental math games. There are two primary ways to prepare for the mental math online assessment.
- Repitively play mental math games until you start building mathematical intuition and recognizing patterns.
- Deliberately study the numerical tricks on how to quickly perform calculations in different scenarios.
While the former is self-explanatory, it can take quite a long time to accomplish, depending on the mathematical rigor you currently possess. The latter option, however, presents an approach that may be more accessible to anyone looking to get started with their preparation. It's important to note that in both approaches, you must still practice with timed assessments. If you are interested in practicing such tests, we recommend playing our trader math game.
If you choose to follow approach #2, here is a list of great resources to help you learn mental math tricks:
Secrets of Mental Math - in this book, Arthur Benjamin shares his tricks for making quick calculations on complex equations. This book doesn't expect you to already have advanced mathematics knowledge, and therefore is quite approachable for a general audience.
Short-Cut Math - in this book, Gerard Kelly teaches 150 math shortcuts to easily perform addition, subtraction, multiplication, and division quickly. The brevity of this book makes it a good read if you're short on time to prepare for your upcoming interview.
How to Calculate Quickly - in this book, Henry Sticker teaches methods to master addition, subtraction, multiplication, division, and fractions. The book contains 9,000 short problems with solutions to provide you with the adequate practice for your interviews.
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