All the students have had their fair share of mathematics in school and college, but when it comes to solving aptitude questions, they struggle. The main reason they struggle is a time constraint. A simple math question can be solved by everyone, but if you have 50 questions to solve in 60 minutes, then your speed should be really good. I am not talking about your problem-solving speed, I am talking about adopting some methods that reduce your calculations dramatically and enable you to arrive at the answer in a fraction of the time you were spending earlier. In other words, you need to analyze different ways to solve quantitative aptitude questions and use the fastest among them. Therefore, I bring you some of the most important quantitative aptitude tricks.
If you haven’t checked my other post on tricks to solve logical reasoning questions effectively & planning to attempt any exam, then it’s definitely worth checking out. Because you also need to have reasoning skills along with quantitative aptitude tricks to crack the exam.
Extremely important Quantitative Aptitude Tricks:
Use the options given to solve
In a lot of quantitative aptitude questions, you can analyze the options given and easily eliminate the ones which cannot be justified by the question. Here is an example for you.
Question: Ages of A and B are in the ratio 7:4, after 5 years, the ratio becomes 11:7. What is the age of A?
Options: A. 11, B. 18, C. 21, D. 28
Now, you know the age of A must be a multiple of 7, and you can quickly eliminate option A and B.
Now pay attention to option C, if we take the age of A as 21, then after 5 years, A will be 26 years old. However, 26 is not a multiple of 11, and according to the question, A’s age after 5 years should be a multiple of 11. There you go, eliminate option C too.
Now you’re only left with option D which is the answer. 28 is indeed a multiple of 7 and after 5 years it would become 33, which happens to be a multiple of 11.
Don’t compute everything, use options to identify
If you are given a complex calculation to do, just think for a second, there has to be a better way to do it. Because complex calculations are not tested in an aptitude test, your smartness is. Below is an example for more clarity.
Question: 3812 + 5972 = ?
Options: A. 456284, B. 658598, C. 765454, D. 501570
Now, to arrive at your answer, you can either manually calculate the squares or you can think in a smarter way.
Square of 381 will definitely have the last digit of 1.
(11)2; is 121, (21)2 is 441, (31)2 is 961, and so on. So, 3812 would be something like this xxxxx1. Similarly, (597)2 would be something like this, xxxxx9. Without calculating the full number, we just focus on the unit digit.
72 is 49, and the last digit is 9, so 5972 has to end with 9.
Now that you have 2 numbers, xxxxx1 and xxxxx9, just add them like an old-fashioned addition question.
This way, you know the answer will end with 0, and now look at the options, your answer is D. Quantitative aptitude questions are a cakewalk if you’re equipped with skills like these. Get yourself a mathematics home tuition to develop your skills while you still have time.
Use effective percentage
The concept of effective percentage can help to reduce your calculation time dramatically.
You must have seen poster and banners outside shops offering 50% + 30% discount. The same kind of questions can be seen in most aptitude tests.
This offer means, first you will calculate 50% of the MRP, and then apply a 30% discount on the new value (it is not straight 80%).
If a product is worth 100 rupees, then first apply 50% discount. You will arrive at 50 rupees, now apply 30% discount, and you will arrive at 35.
An alternate way of doing this is to use effective percentage. And the formula goes:
a + b + ab/100 (where a and b are the percentage rates)
= (-)50 + (-)30 + (-50)(- 30)/100
= -80 + 1500/100
It means, that 50% off + 30% off actually means flat 65% off on MRP.
65% off on 100 is 35, which is the correct answer we arrived at earlier.
Now, I added a (-) sign at the beginning of percentages, because they are discounts, we are reducing the amount of 100, not increasing it. Had there been a question of compound interest where the amount gets increased, you would a (+) sign. This way, the effective percentage can be used in more than one topic, discounts, compound interest, etc.
Learn basic percentages
If you want to calculate 10% of something, you would cut the zero at the end, or put a decimal. This much is known by most people and they don’t do (Number x 10/100).
But what to do when you want to calculate 25% of a number? Or 76% of a number?You must be equipped with basic percentage
rules to solve these things quickly.
25% is nothing but 1/4th of a number.
75% would be 3/4th of a number.
Just calculate 3/4th of your given number and you will arrive at 75%. Now, calculate 1% by either cutting 2 zeroes from the end of your number, or by putting a decimal before 2 places at the end. Once you have that 1%, add it to the 75% which you got earlier.
There you go, instead of doing (number x 76/100) and wasting precious time, you are now solving another question.