Name: 【TEDx】Faster than a calculator | Arthur Benjamin | TEDxOxford
Uploaded: 2017-11-10T15:05:51.000Z
Duration: 15 min 4 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Translator: Mohammed Basheer Reviewer: Nadine Hennig

my name is Art Benjamin and I am a "mathemagician".

What that means is I combine my loves of math -

and magic to do what I call "mathemagics".

I've got a quick question for the audience.

By any chance, did anyone here in the audience

happen to bring with them this afternoon a calculator?

If you have one, perhaps on your phone, or somewhere,

and you're pretty comfortable using it, raise your hand.

I'll need a couple of people to help me out here.

I see one... two... and perhaps one more... three.

With the three of you, bring out your calculators and join me up here on stage,

and let's give these volunteers a nice round of applause.

Since I have not had the chance to work with these calculators,

I need to make sure that they are all working properly.

Would somebody get us started by giving us a two-digit number, please?

How about a two-digit number? Just yell one out.

Arthur Benjamin: Oh, okay. That's fine! 74

And another... how about another two-digit number?

AB: 39. Multiply 74 times 39 on the calculator.

Make sure you get 2,886, or the calculators are not working.

Do each of you get 2,886? Give them a round of applause!

I noticed that took some of us a little bit of time to get the answer.

I'll give you a shortcut for multiplying even faster on the calculator.

There's something called "the square of a number"

which most of you know is taking a number

On most of these calculators, they've little shortcut buttons

that allow you to square numbers even faster.

What I'm going to try and do is to square -

and you might test it - make sure you could square 5 or 6 with it,

is to square in my head, three two-digit numbers

faster than they can do on their calculators,

But I'll ask these three people in the third row - one, two, three.

and if you would square the first one, the second, and the third one,

AB: 26. Would you call out your answers, please?

Let me try to take this one step further.

I'm going to try to square some three-digit numbers.

This time, I won't even write these down.

I'll just call them out as they're called out to me.

Anyone at all call out a three-digit number,

If I get the answer right, give me a big thumbs up.

If I make a mistake, let me know, and I'll try and fix it.

How about another three-digit number, sir! a three-digit number?

AB: 103 is 10,609. Way too easy! Another three-digit number, please?

AB: 125 is 15,625, but that's 5 to the 6th power, so that was easy too.

How about another three-digit number, sir?

AB: 985 is 970,225. Yes, thumbs up, if it's right.

Subtitles ListPlay Video

【TEDx】Faster than a calculator | Arthur Benjamin | TEDxOxford

tricky

attempt

audience

applause