- #1

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How to do this in 10 seconds without a calculator and scratch paper?

1565 x 1197 = ?

1565 x 1197 = ?

- Thread starter Jekertee
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- #1

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How to do this in 10 seconds without a calculator and scratch paper?

1565 x 1197 = ?

1565 x 1197 = ?

- #2

mgb_phys

Science Advisor

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Call it 1565 * 1200 which is just (1565 * 2 *100) + 1565*1000

The subtract 1565 three times.

The subtract 1565 three times.

- #3

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Do you know how to apply Indian's classic calculation method to this ?

- #4

mgb_phys

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Sorry never heard of it.

- #5

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Ask google - it takes less than 5 seconds!How to do this in 10 seconds without a calculator and scratch paper?

1565 x 1197 = ?

- #6

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I don't think that'll work.

- #7

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I googled 1565 x 1197, and got the answer: 1 873 305.

It didn't take 10 seconds. Then I googled "India's classic calculation method" but I got nothing I could use.

Jekertee, are you willing to teach us the method?

It didn't take 10 seconds. Then I googled "India's classic calculation method" but I got nothing I could use.

Jekertee, are you willing to teach us the method?

Last edited:

- #8

DaveC426913

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- #9

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:shy , Jim, I din't know that method also, I made a quizz thinking that someone knew to tell me too.....

Jekertee, are you willing to teach us the method?

I input random numbers into the search box of google but found only strange result. It's amazing to me the example I gave works on your search

- #10

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Only numbers? Didn't you specify an operator?...I input random numbers into the search box of google but found only strange result.

What about an expression like (into the search box):

2*17.9 + 3**3

- #11

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Is there any information you could give us to help search for it?I din't know that method also, I made a quizz thinking that someone knew to tell me too

- #12

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4 x 1565 = 6000 + 240 + 20 = 6260

6260 x 300 - (1565 x 3) = ?

6260 x 3 = 18000 + 600 + 180 = 18780

18780 x 100 = 1878000 - (1565 x 3)

1565 x 3 = 4500 + 180 + 15 = 4695

1878000 - 4695 = ?

=1873305

This is one way, and it's probably not the fastest, but it uses an ancient technique of multiplying where one number was halved, and the other was doubled. Or multiplied by 3, and divided by 3.

- #13

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for example:

when multiplying 2, 2-digit numbers with the same tens digits and two ones digits that add up to 10, (ex. 23 x 27 ) the vedic stuff is useful.

you just multiply the tens digit by the next number up, so multiply 2 by 3 and get 6.

then multiply the two ones digits, and get 21.

the answer is 621.

there's tons of little things like that that you can find on google.

- #14

- 918

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Yes, here's a proof. Let a be the common tens place digit (2 in this case), and b one of the ones place digits (either 3, or 7 in this case). Thenwhen multiplying 2, 2-digit numbers with the same tens digits and two ones digits that add up to 10, (ex. 23 x 27 ) the vedic stuff is useful.

you just multiply the tens digit by the next number up, so multiply 2 by 3 and get 6.

then multiply the two ones digits, and get 21.

the answer is 621.

[tex](10a + b)(10a + 10 - b)[/tex]

[tex]= 100a^2 + 100a - 10ab + 10ba + 10b - b^2[/tex]

[tex]= 100a(a + 1) + b(10 - b)[/tex]

That is to say, multiply a by the next number up, multiply by 100 and add the product of the two numbers in the respective ones places.

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