Mental Math Tricks for Superfast Calculations
- Jan 04, 2015
- LearnPick
Did you say ‘Mental Math’? How many of you loved solving those cunning Mental Math sums in your third standard? And, can the human mind really offer Mathematical solutions? Well, if all of us were indeed capable of working out tough calculations in our mind, why were calculators invented? Puzzled, aren’t you?
If you are, don’t hesitate to admit it, friends. For, the truth is, Math can be quite intimidating most of the times. After all, you can’t be a second ‘Arthur Benjamin’ - the famous American mathematician who can tell you the square of a five-digit number in seconds. Try listening to some of his TED talks on Math, if you are curious to improve your skills in this subject.
I’ll be frank with you guys. This subject, Math, was never my cup of tea in my student-life. When I was in school, I remember staring helplessly at the pages of my Mental Math book, whenever the teacher asked me to solve its sums. To me, Math was to me what Lord Voldemort was to Harry Potter! I was clueless about how solving Math sums is a cakewalk for some people. Then, one fine morning, I stumbled upon some Math tricks for performing superfast calculations.
Want to know what they are? Read on!
- Tip to Multiply double-digit numbers by 11: Simple calculations like multiplications, subtraction, addition and division can be solved in seconds, using the principle of Vedic Math. So, how do you obtain the result of a number if you multiply it by 11? I’ll tell you how. Just add the two digits of the number which you want to multiply by 11. Next, place the sum of the digits in the center of the original number. Now, if this sum is 10 or more, carry it over.
For instance, you wish to multiply 68 by 11. So, add the digits, 6 + 8. You get 14 when you add them. Then, keep it between the digits 6 and 8, what gives you 6148. But, remember, I told you that you must carry the one over. Do it. You will get 748 as the answer. Check it with a calculator and you will find it’s the right answer!
- Tip to Multiply numbers close to the power of 10: Wasn’t the first one fun enough? But, how to multiply double digits to numbers which are quite close to power of 10? Let me demonstrate the trick with an example.
Suppose, you have to calculate the answer of 99 x 97. Do not fret, my friends. All you need to do is subtract 100 from 97. (99 – 100) = -01.Then, you must subtract 97 from 100. You get -03.Next, to get the first digit of the answer, add 99 + -03. The answer to it is 96. On the other hand, if you 97 + -01 you also get the same answer, that is 96. In other words, you have to cross-add a single set of numbers.We come to the last step finally. Multiply the numbers -03 x -01 which equals to 03. Therefore, the final answer would be 9603.Okay, so that’s the way to try out multiplications mentally. Now, let me teach you how you can perform other calculations, like additions and subtractions. This is particularly helpful for students who are very young and make Math fun for kids.
- Tip to solve sums which require you to add the digit 5: I want to share an easy way of adding 5 to a digit which is greater than this number. Say, you have to add 8 + 5. You can solve it fast only if you subtract 5 from 8. Then, you must add 10 to the answer you get.
For instance, you are adding up 8 and 5. First subtract 5 from 8. The answer is 3. Then, just add 10 to it. Meaning, 3 + 10 = 13. So, your answer is 13. How simple is that, isn’t it?
- Tip to solve sums which require you to subtract 5: Now that you can mentally solve any sum which requires you to add 5 with a number, let us see how to solve sums which subtracts 5 from any digit.
Suppose, you need to subtract 5 from 24. Remember the rule for subtracting the digit 5 from any number whose last digit is smaller than 5. The rule is: add 5 to 24 (24 + 5). It equals to 29. And then, you just have to subtract 10 from the answer. 29 – 10 = 19. And, yeah, that is the accurate answer. It is that easy.Feeling a bit confident now? Now you know the technique of addition, subtraction and multiplication. Why not learn some tips to go about easy division as well? Here you go!
- Tip to divide any number by 5: Do you know the secret to dividing any number by 5? Friends, you must pay attention to this one. It is interesting.
For instance, you have to divide 1475 by 5. What would you do? Simple! Just multiply 1475 x 2. It gives you 2950. The rule is similar to the ones used in addition and subtraction. Can you recall what it is? I am reminding you. You must divide your answer (2950) by 10. You get 295. So, that’s exactly what your answer is.
I have let the cat out of the bag now. So now, I am pretty certain that Mental Math would not continue to be scary for you. Why not try out these exciting tips today to master Mental Math? Practise makes a man perfect. Hope you are familiar with this popular proverb? So, keep practicing these Mental Math tricks for speeding up your calculations. And soon you will realize that you have forgotten the use of calculators.Welcome to the smarter you!
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