an amazing "mathemagician"

[BERIGAN]

http://static.videoegg.com/ted/flash/fulls...cid=/ted/movies

[BruceH]

The link doesn't work.

[rockefeller center]

The link doesn't work.

Try again, it does work.

Whoa! Thanks, Berigan.

[Aggie87]

Impressive!

[RDK]

Easy. They're all plants!

[Harold_Z]

Great stuff!

Thanks Berigan.

[gnhrtg]

Interesting. Thanks.

[Joe G]

The guy's good.

[BruceH]

He's a number-whizz!

Thanks Berigan!

[Adam]

I'm halfway through. No magic yet. Good mind for squares.

But the second trick where he had each of them multiply 8649 by a 3 digit number is pretty easy. 8+6+4+9 = 27, 2+7 = 9

Now as I recall, a number whose digits equal 9 when multiplied will always create a number whose digits add to 9.

so when the folks give him 6 of the 7 digits in any order, it's just simple addition to figure out the last digit.

For example, 8649 x 456 =3943944. 3+9+4+3+9+4+4= 36, 3+6 = 9

So if the person said "3, 9, 4, 4, 4, 9" that would equal 33, which =6. 9-6=3. So he woudl call out "3" as the missing digit.

Am I right?

[BruceH]

Say what now?

[Patrick]

Adam is correct.

Could this guy name the last two digits after hearing any 5 of them (in any order)?

I seriously doubt it.

[Aggie87]

I'm halfway through. No magic yet. Good mind for squares.

But the second trick where he had each of them multiply 8649 by a 3 digit number is pretty easy. 8+6+4+9 = 27, 2+7 = 9

Now as I recall, a number whose digits equal 9 when multiplied will always create a number whose digits add to 9.

so when the folks give him 6 of the 7 digits in any order, it's just simple addition to figure out the last digit.

For example, 8649 x 456 =3943944. 3+9+4+3+9+4+4= 36, 3+6 = 9

So if the person said "3, 9, 4, 4, 4, 9" that would equal 33, which =6. 9-6=3. So he woudl call out "3" as the missing digit.

Am I right?

I think you may be right too, but how would he handle all of the *other* numbers that don't add up to 9? They don't have a corresponding rule like that.

He'll only get lucky that they give him a number that adds up to 9 about 10% of the time on average.