Introduction to mental arithmetic

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% 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 are multiple choice, so 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, you ar NOT allowed to use a calculator.

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 keep the duration of the tests at 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. *Trading Interview* provides you the Medium-mode on the mental arithmetic questions, which contains non-round numbers. The last step is to exercise with fractions and ‘filling the gaps’, which is the Hard-mode on this website.

How do the three quizzes work?

You try to solve as many questions within the chosen time-limit. There is no end on the question. If you solve a question, a new question will appear. We chose that it would be better to make the quizes answer field open, so, without a multiple choice. We think that the time that you will lose on the real test while looking for a multiple choice answer is the same as the time you would lose on this website while looking for the numbers on your keyboard. Therefore, we don’t want you to lose extra time on submitting an answer. This gives you the most realistic point of view on how far you are with your preparations.

What is the benchmark for the three 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: 20+
- Medium: 15+
- Hard: 10+

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.