Mental Calculations for Numerical Reasoning

A great deal of candidates sees quantitative reasoning as an assessment of arithmetic knowledge. While acquaintance with maths is critical to your success such tests are not designed to capture your educational achievements but rather to assess your innate capabilities and intellect to mentally manipulate and calculate facts and figures in methodical way. Hence, it is inevitable that you train and stretch your inner thinking to process and handle wide range of data in quickly and accurately. Such practice will not only pay off at your numerical tests but also in your everyday life as you will be far better off to deal with and analyse all sorts of data trends or cycles often found in management, financial or economic reports. Below you can find some practical examples of how to use your mental calculation skills to examine and swift through substantial set of data presented in tables, charts or graphs.

The below question employs your mental arithmetic aptitude and evaluates your skills to absorb and mentally calculate extensive amount of data. It presents you with five projects and requires you to identify one that had the highest percentage profit. The correct way to deal with these types of challenges is to quickly filter out answers that are likely to be incorrect and only focus your efforts on relevant and applicable information. To work out such questions in quantitative or numeracy tests you may follow three simple steps as below.

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Which project had the highest percentage profit?

Note that by thorough inspection and mental calculation you can conclude that Project B, C and E would have the lowest percent profit compared to Project A and D; but how do we know this? Well, to find out you need to look for projects with lowest proportional costs to revenue. Starting with Project A; you can easily spot that the percentage revenue is 70 that is (21 / 30) x 100; whereas turnovers of Projects B, C and E would be lower as the profit to revenue ratio would be fairly low. Now looking at the percent proceeds of project D which works out to 60% that is (3 / 5) x 100 you may conclude that project A must have had the highest proportional profit. Remember, in your numerical reasoning test you must attempt to make as many mental calculations as possible in your head and input into your calculator only the data that deviate marginally.If you find this a challenge then you may want to see chapter on how to improve mental reasoning skills.

Now consider the second question. If you feel more confident then set your timer for 60 seconds and try to work out.

Which project had the lowest revenue to costs ratio?

By quick mental calculation and estimation of total revenue and total costs of all projects you can quickly conclude that Project B and E must have had the lower ratio than project A, C and D. That is for project:

Hence for your calculations you can rule out project A, C and D and save time by not imputing data into your calculator for these three projects. To get the correct answer use your calculator only to calculate ratio of Projects B and Project E as the revenue to cost ratio of these are lowest and most similar. Hope that this provided you good example how to think and perform mental calculations in your numerical reasoning tests.