MATT PARKER: All right.
I'm going to show you
a math card trick.
It is a genuine math trick,
there's no sleight of hand,
there's no YouTubery.
It's not a sneaky edit or
anything like that.
Everything you see is
the whole trick.
It's nothing else.
And also because it is a math
card trick, it will involve a
lot of tedious counting.
So this is how this
is going to work.
I have a normal deck
of cards, there are
all 52 cards in there.
I'm going to look through.
What I'm going to do is pick one
of the cards and memorize
where it is in the deck.
So I'm going to pick one of
these cards, and then what I'm
going to do is count how many
cards are on top of it.
And I'm going to remember both
the card I'm thinking of, and
the number of cards above it.
OK, got it, got it.
OK, so I'll remember.
I'm remembering one card in this
deck, and I'm remembering
where it is.
What I'm going to do now is
I'm going to broadcast the
number of card into
Brady's mind.
All right?
So I'm thinking of a
number of cards.
I'm going to send that
number into his mind.
He's going to tell me that
number that I've sent to him,
and then we're going to
count off that many.
And the next one will be the
card I'm remembering.
Skeptical people may say you're
just going to change
your mind to whatever the card
happens to be, so I'm going to
write down.
In fact, I will show--
How can we do this?
BRADY HARAN: [INAUDIBLE].
MATT PARKER: Yeah,
if you leave.
If I-- oh, brilliant.
OK.
If I take--
OK, so we're going to
kick Brady out.
He's going to leave the room.
Just briefly.
Over here, this is
my prediction.
So I'm going to predict
this card here.
OK, that one there.
Cool.
And then if I fold this up.
BRADY HARAN: OK?
MATT PARKER: Hang on a second.
Hang on.
OK, you can't see that.
Actually, I'll put
it down there.
OK, cool.
Yep, yep, you're good.
You're good.
So, I wrote it down on
a piece of paper.
I openly scrunched it
up with one hand and
I put it down there.
But everyone has seen the
card I'm thinking of.
So now, when I send this number
into your mind, the
number, I'm going to count off
that many cards, and bam, the
next one will be the one
that I wrote down
on that piece paper.
And in case it goes wrong, I
reserve the right to do this
up to twice.
At that point, we'll
just call it off.
OK, so here we go.
Here comes the number, Brady.
What is it?
BRADY HARAN: 12.
MATT PARKER: 12.
OK, so I'm going to take off 12
cards, the next one will be
the one that I wrote down.
Here we go, ready?
1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12.
OK, next card.
Next card is the
King of Spades.
I did not write down
the King of Spades.
That is not the card
I wrote down.
But I tell you what,
we'll try again.
We'll try again.
We'll do one more time.
So, ready?
OK, ready?
What's the number?
Here it comes.
BRADY HARAN: 15.
MATT PARKER: 15 this time.
OK, here we go.
15, are you ready?
Here we go.
1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15.
OK, here we go.
Did I write down, did I write
down the 4 of Spades?
I did not.
I did not write down
the 4 of Spades.
What I actually wrote down
was the 8 of Diamonds.
And you might think that this
trick is a bit of a bust.
You tried to guess the number
twice, you said 12 the first
time, you said 15
the second time.
It wasn't at either of
those positions.
It turns out giving you one
number in your mind would be
slightly impressive, sending
you two numbers
would be even better.
If you changed your mind even
slightly on either of those
numbers, the difference wouldn't
have been three.
You actually had to take three
cards off, and then
it's the next one.
And again, if you hadn't
said 12 and 15, we
wouldn't have got 3.
Are you ready?
1, 2, 3.
The next card is the
8 of Diamonds.
And now I just look
smug for a while.
That's my trick where I send
numbers into someone's brain.
Yeah, OK.
It's always, to be fair, every
time you do the trick, you
have to deal it out twice.
You have to put it back together
each time, and it
always ends up being
the difference
between the two numbers.
And obviously, this started
off in a very particular
position, and it was a position
where, by dealing it
out twice, it always ends
up at the difference.
There i one slight tweak,
depending on if the second
number the person says was
bigger or smaller than the
first number, and so you have
to do something slightly
different in that case.
But if you get a pack of cards
and you have a bit of a play
with it, you'll be
able to work it
out reasonably quickly.
OK, if you're still here,
I'll explain most of
how the trick works.
And so what I did, when I looked
through the cards, I
was looking for them.
And to be honest, I wasn't
counting or anything, I was
just looking to see what
the top card was.
And as we know, it was
the 8 of Diamonds.
So you look through, see what
the top card is, that's the
card you write down.
So now, when you start sending
numbers into someone's brain,
you've got to pay attention to
what happens to the top card.
So Brady, the first number
he said was 12.
And so when I start counting
12, the top card off is the
chosen card.
1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12.
And when you count cards off
into a pile, you're reversing
their order.
Because what was the top
card is now the bottom
card of this pile.
And a lot of maths magic tricks
use the fact that you
reverse cards when you
deal them out.
So when I put them back
together, the 8 of Diamonds
will now become the 12th
card from the top.
In fact, whatever number your
volunteer says first, it will
end up being that card
from the top.
And so now, Brady picked 15,
which was a bigger number.
And so as I count to 15, first
of all I have to count up to
12 to get to 15.
So 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, and as the 12th card
comes off, that was our original
8 of Diamonds.
Because we've just reversed
12 again.
And then you count 13, 14, 15.
And so in fact, I've got to put
three more cards on top to
go from 12 to 15.
I have to put the difference of
the two numbers on top to
go from the first number to
get to the second number.
And when I put them back
together now, all I have to do
is take off those three.
So I take off the difference.
1, 2, 3.
And the next card is
our friend, the
8 of Diamonds again.
And so no matter what two
numbers they say, as long as
the first one's smaller, the
first time you deal, it puts
it into that position.
The second time you deal, it
reverses it back to the
original order, and then you
put the extra ones on top.
Once you take those off,
it's right there.
If you're still watching, then
you want to work out what
happens when the second
number is smaller
than the first number.
So I'll show you again.
So we'll pretend Brady did the
same thing, but he said 15
first, then 12 second.
So there's the 8 of Diamonds,
it's still on top.
So first of all, 15.
OK, so 1.
There's the 8.
1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15.
I put it back on top.
Now, the trouble is if the
second number's smaller,
you're not going to get back
to the chosen card.
You're just not going
to get far enough.
But what you will do is you'll
take off, well, let's say 12.
1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12.
And then obviously you're going
to do the thing with oh,
no, that's not it.
It didn't work, boo hoo.
The trick now is instead of
putting these back on top, put
them underneath.
Because now you've put it into
the 15th position, which is
the first big number.
You've then taken
away that 12.
In fact, it's still the
difference between the two
numbers, with one slight,
subtle change.
Instead of taking off that many
cards and then the next
one, you take off that many
cards as the last one.
I'll show you.
So in this case, I would say oh,
you picked 15 and 12, the
difference is 3.
Wow, it's actually
the third card.
Here we go, ready?
1, 2, 3.
And there it is.
It's the third card.
And so it's still the
difference, but all you need
to do is make sure, instead of
counting off all of them first
and then revealing it, you count
them off and turn over
the last one.
OK.
What if they pick the
same number twice?
Now, if they pick the same
number twice, then what you
need to do is--
I mean obviously, you can play
off the fact that they're
very, very insistent that
that's the number.
And you say look, you seem
very insistent mean.
In fact, you're right.
That is the number
I was sending.
Something just went wrong
the first time,
so I doubted myself.
But you know what, it probably
is that number.
Then you count them off again,
and the important thing is
this time you count off that
many times, and then you turn
over the last one
you're counting.
So I'll show you very quickly.
So 8 was the top.
Let's say Brady said
12 the first time.
1, 2, 3, 4, 5, 6, 7,
9, 9, 10, 11, 12.
Oh no, I got it wrong.
I'll put them back on again.
And then he's like
no, no, I insist.
It's definitely 12.
You go OK, well we'll check.
Maybe it's just the 12th card.
Maybe that's the number I'm
trying to send you.
1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12.
Oh, it is.
Wow, how about that?
It still works.
So there you are.
That's what you do if they say
the same number twice.
JAMES CLEWETT: Here we go.
Here's my home made
lottery balls.
I'm going to give them
a little shake.
And I'm looking away because
I really don't
want to cheat here.
Looking away.
I've got one hand in there.
I'm pulling out a ball,
and it's number two.
MATT PARKER: Yes, there
is one more option.
What if they say 1 or 0 at
the very, very beginning?
And if they say 1 or 0 at the
very, very beginning, this is
perfect, right?
And this has actually
happened to me.
Twice now, someone said
1, it's the top card.
And so what you do is you go,
really, the top card?
You really think
I just put it--
And t hey go yeah, I'm
absolutely certain.
You go, well good, I'm glad
you're certain, because it is
the top card.
And then their brain blows up.
It's absolutely amazing.
And I think that is
all the options.
