Vedic maths isn't maths. It's just a collection of tricks to do calculations fast in your head. And the tricks aren’t that great either!
Most of the tricks (that I came across) are simple extensions of algebraic identities. It really takes 2 minutes to prove them.
Let’s look at an example: Multiply by 11:
Let’s say the 3 digit number we want to multiply is N=100⋅a+10⋅b+c.N=100⋅a+10⋅b+c.Then,
N∗11=N∗(10+1)N∗11=N∗(10+1)
=10∗N+N=10∗N+N
=(1000⋅a+100⋅b+10⋅c)+(100⋅a+10⋅b+c)=(1000⋅a+100⋅b+10⋅c)+(100⋅a+10⋅b+c)
=1000⋅a+100⋅(a+b)+10⋅(b+c)+d=1000⋅a+100⋅(a+b)+10⋅(b+c)+d
This is precisely what you get. For instance if N=712,N=712, then a=7,b=1,c=2.a=7,b=1,c=2. Thus,
11∗N=11∗N= ‘a’ ‘a+b’ ‘b+c’ ‘d’ == ‘7’ ‘8’ ‘3’ ‘2’ =7832=7832
Why is Vedic maths useless?
Why do you need to do calculations fast when you have a calculator? Why do you need to remember a bunch of tricks and rules, when you already know the principle of multiplication?
And you know the funny thing with tricks; you forget them if you stop using them.
Maths is not about remembering formulas. It never was. It’s about application and understanding of concepts. You need to remember just the absolute basics and rest you can do it in your head or on a piece of paper.
For instance, do you think I remember the ugly series expansions of functions like log(x),sin(x),exlog(x),sin(x),ex? No, I derive them on the go using Taylor series expansion. You don’t need to remember it.
Why is Vedic maths often talked about?
I never studied Vedic maths until I prepared for CAT. I soon realized how much I needed to remember just for some simple calculations. I worked out the internals of the tricks and never used it ever again.
And I believe, its preponderance is due to the way subjects are taught to us in schools.
Remember everything you can and it’ll fetch you marks. There are so many things I had to mug in my 12th standard, only to realize it later that I really didn’t need to.
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