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# Do you multiply this way!

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Before my college days I used to multiply orthodoxly by this way.

But as time passed, I learned new things. I remember, In a Hindi magazine named “Bhaskar Lakshya”, I read an article in which a lecturer (apology, I don’t remember his name) had suggested how to multiply in single line (row). Today I thought that I should share this method on MY DIGITAL NOTEBOOK too.
I know there are many, who already know this method, but I think maximum people wouldn’t have any idea about this method. I found multiplicating this way, very faster – easier and smarter. The ‘only’ requirements for using this method is quick summation. You should be good in calculation and addition. Smarter your calculations, faster you’re.
I’ll try to illustrate this method below. If you had any problems regarding language (poor off-course) and understandings, please feel free to put that into comments.

Let we try to multiply 498 with 753.
$\, 4 \ 9 \ 8\\ \times 7 \ 5 \ 3$

# Step I

Multiply 8 and 3 and write the unit digit of result carrying other digits for next step. The same is to be done with each step.

# Step 5

The overall work looks like:

I don’t know if there is any algorithm behind it. The pattern of calculation is very obvious, making crosses and adding numbers.
You can use this method, multiplying larger numbers too. Try this one at your own. Steps are marked for convenience.

Images were created by Microsoft Paint software except very first image which is taken from wikihow.com.

1. [...] Do you multiply this way! (wpgaurav.wordpress.com) [...]

2. Hi Gaurav, I use this method as my primary method for multiplication, it really easy and works well. I never thought about the algorithm, but now as you noted there must be one, I just wrote it down. Here is it: Note that AB actually means 10a+b. e.gs.89=10×8+9
(10x+y)(10a+b)
=100ax+10bx+10ay+by
=100ax+10(ay+bx)+by
This is for multiplication of 2-digit number by 2-digit numbers; this can be proved for any number for that matter. This is precisely what we do!
X Y
x A B
—————————
AX (AY+BX) BY
I don’t know who to do mathematical formatting in blogs, but I guess you will get it!

3. I got it. You could use your latex code here by writting $latex Your LaTeX code$.

• Manish says:

Great work!!
Now, I should reopen my mathematics books.

4. [...] asks, “Do you multiply this way?” My challenge: Don’t memorize this method as a trick, but study until you see why it [...]