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  • Nameste.

  • I'm from India,

  • and India is one of the oldest civilizations in the world.

  • It has contributed to the world

  • concepts such as yoga,

  • ayurveda,

  • spicy chicken tikka,

  • and Vedic math.

  • Vedic math is one of the world's easiest

  • and simplest way to do math.

  • We are going to combine together

  • and do some number crunching today.

  • So what we are going to first do is multiply by 11.

  • We're going to do it together,

  • so if you blink, you're going to miss it.

  • So just watch it, OK.

  • So we're going to do 32 times 11, OK.

  • So we split 3, and we split 2,

  • and we add 3 and 2 and paste it on top,

  • and we get the answer as 352.

  • That's it.

  • Let's try another sum.

  • 45 times 11.

  • Let's hear it.

  • Exactly, that's 495.

  • And 75 times 11.

  • So it gives you 7,125,

  • 1 gets carried over and it becomes 825.

  • That's how simple it is.

  • OK, this is the principle behind it

  • where a is the coefficient.

  • Let's move on.

  • OK, now what we're going to do is the base method.

  • OK, this is used to multiply numbers

  • very close to the powers of 10,

  • like 10, 100, 1,000, and so on.

  • So we have a sum here, say 99 times 97.

  • OK, now tell me, is 99 more than 100 or less than 100?

  • Less by how much?

  • So we write minus 01.

  • And 97 is less than 100 by how much?

  • So we write minus 03.

  • So what we're going to do is

  • we're going to cross subtract

  • and get the first part of the answer, like this.

  • We're going to do cross subtraction.

  • 97 minus 01 would give us

  • 96.

  • and we multiply 03 times 01 vertically,

  • and we get an answer of 03.

  • Let's check another sum.

  • Try and do it yourselves.

  • We got 98, which is,

  • is it more than a 100, less than 100?

  • By how much?

  • And 97 is 3.

  • So we got 98,

  • we go crosswise,

  • we got 98 minus 3,

  • or we can do 97 minus 2,

  • they'll all give you the same answer.

  • So that would give us 95.

  • And the second part would be

  • 06.

  • So that's our answer.

  • OK, let's take a bigger number.

  • Let's try this one.

  • Here the base is 1,000.

  • So we got -004,

  • and 997 would be

  • -003.

  • We go crosswise like this,

  • and we get 996 minus 003 would give us

  • 993,

  • and 004 times 003 would give us

  • 012.

  • And that's our answer.

  • Thank you.

  • 14 times 12.

  • OK, here the base is 10.

  • OK, so is 14 more than 10 or less than 10?

  • More, so we got plus 4,

  • and 12, we got plus 2.

  • Again, we apply the same rule,

  • so we do 12 plus 4,

  • which gives us 16, like this.

  • And we multiply 2 and 4, that gives us 8.

  • So now, all of us here,

  • we're going to do mental squaring, OK.

  • Everybody is going to participate here,

  • and we're going to do squares of numbers

  • more than 100 mentally right now.

  • So we got 101,

  • OK, now visualize on the board,

  • what's going to be on the right hand side.

  • Plus 01, so we got that.

  • OK, now we add plus sides, right?

  • Yes? No?

  • So we got 101 plus 01,

  • that would give us

  • 102,

  • and, see here, like this.

  • And 01 is getting squared, right?

  • So that would give us

  • 01, and that's your answer.

  • Try the next one.

  • Let's try 102 squared.

  • Let's try, everybody.

  • So 100,

  • so 102 would be

  • 10404.

  • OK, now the next one, try it everybody together.

  • I'll give you 5 seconds.

  • OK, let's say it together, let's say it together, OK.

  • [10609]

  • 10609 and that's the answer.

  • Woo!

  • 104 squared, how much would that be?

  • Calculate it, 5 seconds.

  • Come on, girls in the back.

  • OK, so the answer would be

  • 10816.

  • OK, let's do the next one: 105 squared.

  • Oh, no, no, no, no,

  • we're going to try over, we're going to try over, OK?

  • OK. I'll give you 5 seconds, just think about it.

  • OK, now we're going to go, OK?

  • 11025.

  • OK, let's going to do the next one, 106 squared.

  • Try it, come one, everybody, it's simple and easy.

  • [11236]

  • OK, let's do it one more time.

  • 11236.

  • Now 107, think, hold on, don't say anything out loud,

  • just think mentally,

  • 107 squared.

  • OK, now let's say it out loud.

  • 11449.

  • And 108 squared.

  • [11664]

  • Fantastic, give yourself a round of applause, come on!

  • And this is the principle behind this,

  • where a and b are the excesses

  • or the deficiency from the base.

  • I'm going to teach you

  • in Vedic math, there are 16 sutras,

  • or word formulas, OK.

  • They are very visual

  • and one of them is called, "vertically and crosswise,"

  • through which you can multiply any number

  • by any number in a single line.

  • So I'm going to do a two-digit by a two-digit multiplication.

  • Let's do this.

  • So we got 31 times 12.

  • OK, so we're going to apply

  • the vertically and crosswise sutra.

  • So we're going to do like this:

  • vertically, and then we're going to go crosswise,

  • and then we're going to do vertical again.

  • So, 2 times 1 gives us

  • [2],

  • 2 times 3 gives us

  • [6],

  • and 1 times 1 gives us

  • [1].

  • 6 plus 1,

  • [7].

  • 1 times 3 gives us

  • [3].

  • And that's it, and that's our answer.

  • No more tedious calculations,

  • no more going through the rough work,

  • it's simple in one line.

  • I want to show you a sum again,

  • this time with carry-overs.

  • The same formula, all of us here can do this, OK.

  • Same formula.

  • So let's get started.

  • 4 times 2 gives us

  • [8].

  • OK, now we go crosswise like this,

  • so we're going to multiply 4 times 1,

  • [4],

  • and 3 times 2,

  • [6]

  • 4 plus 6 gives us

  • [10].

  • So we put down 0, carry the 1.

  • And 3 times 1 gives us

  • [3],

  • plus 1,

  • [4].

  • Exactly, that's our answer, 408.

  • OK, thank you for being such a participative audience,

  • and we had a great time number crunching.

  • Now I want to end with a question:

  • whether you'd like math to be dull or boring,

  • or fun and interesting?

  • The choice is yours.

Nameste.

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A2 初級

【TED-Ed】神奇的數學-吠陀數學 (The magic of Vedic math - Gaurav Tekriwal)

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    Zenn 發佈於 2013 年 04 月 28 日
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