Introduction to Mental Arithmetic and Interview Tips

Traders are quick if it comes down to mental arithmetic. Even though the trading scene is transforming into a more algorithmic environment, the vast majority of traders still have to make quick decisions behind their desk. Therefore, the first round of interviews usually contain a mental arithmetic test. To a certain extent, this is something that you can master by exercising. 

What does it look like during an interview?

Several trading firms have a first round that looks as follows: First, you have to do a mental math test in which you get – for example – 80 questions in 7-10 minutes. You need to gather around 60-70% of the points (usually -1 to wrong answers, no penalty for the questions you couldn’t finish, +1 for each good answer) in order to pass to the next round. Examples of some mental arithmetic questions:

  • 2.7 * 60 = … 
  • 3/5 * … = 18/15
  • 468 / 9 = …
  • 234 + … = 718

If you think ‘well, that’s not too hard’, remember: the answers could be multiple choice, in which case you will also lose some time on scrolling through the four possible answers. Sometimes you need to do some extra calculations on the answer itself, for example: the answer on the second question is 6/3. However, the shortest way of writing this is 2, so the multiple-choice answers could contain a 2, and no 6/3. Furthermore, a lot of candidates crack under pressure. How do you deal with the stress to perform?

How to practice

The best way to start exercising is by training on round numbers, like 81/9 = 9. Trading Interview provides you the Easy-mode on the mental arithmetic questions, which only contain round numbers. Try to build up the duration of the tests to a maximum. This way, you can train to keep your focus over a longer period of time. The next step is to train with fractions/ non-round numbers with the Medium-mode. The last step is to exercise with fractions and ‘filling the gaps’, which is the Hard-mode on this website.

All three preset tests have an infinite amount of numbers. When you finish a question, a new question appears. Try to push yourself to new high scores on each test, ideally on the 8 minute durations. This way, you train yourself to keep your concentration as well.

What is the benchmark for the three preset levels?

You may ask yourself during the exercises, when will I be fast enough? Try to keep up with achieving the following scores per level per 2 minutes:

  • Easy: 30+
  • Medium: 15+
  • Hard: 15+

The medium and hard levels are designed with the same target score in mind, but they differ significantly in their focus. The medium level concentrates on decimals, while the hard level presents a broader mix of various mathematical concepts. Interestingly, some candidates might find the medium level more challenging than the hard level, depending on their individual strengths and areas of expertise. Ultimately, the perceived difficulty of each level is subjective and varies from person to person. If you want to improve in specific mental math concepts, use our custom tool (described next).

Custom mental math practice tool

We also offer the customised tool, the Customizable Mental Arithmetic Test, a unique feature to improve your mental calculation skills. This tool is tailor-made to give you control over your learning process. You have the liberty to define the parameters of your test, focusing on the areas you wish to improve.

You can select the arithmetic operators, determine the range of numbers, decide the percentage of decimal included questions, and even set the test’s duration. Whether you want to tackle addition, subtraction, multiplication, division, or fractions, you can customize it all here. Once the test is done, if you’ve signed up for one of our packages, you’ll have access to detailed statistics. This data will provide valuable insights into your performance, tracking your progress, and identifying areas for improvement. Dive in, and take your trading skills to the next level! Read more about the custom mental math practice tool.

Extra tips

Keep track of your scores and try to train it during non-optimal settings: when you are tired or even hungover. The reasoning behind this is as follows. The moment you enter the room for your first test, your nerves will play with you. If you trained before during non-optimal settings, then most probably you will not black out due to nerves during the real test. Read more about this in the following personal experience.