Ok, how does this trick work?

[Hedders]

http://www.digicc.com/fido/

[gmk666]

Witchcraft! Burn Fido! Burn him with fire!

Edited by gmk666 on Monday 2nd February 12:51

[bigandclever]

Maths

[speedy_thrills]

Number = -123

Jumble = -231

Subtract biggest from smallest = -354

Draw a circle around a didget - 35(4)

Type in all number except circled, so 3 and 5.

Says I started with the number "1"?

Genius .

Edited by speedy_thrills on Monday 2nd February 13:00

[Hedders]

speedy_thrills said:

Number = -123

Jumble = -231

Subtract biggest from smallest = -354

Draw a circle around a didget - 35(4)

Type in all number except circled, so 3 and 5.

Says I started with the number "1"?

Genius .

Edited by speedy_thrills on Monday 2nd February 13:00

Subtract smallest from biggest, not vice versa

[speedy_thrills]

Hedders said:

Subtract smallest from biggest, not vice versa

Nearly had me for a second .

[pc.iow]

Got mine wrong aswell, maybe Hedders works for 7up?

Edited by pc.iow on Monday 2nd February 13:21

[Hedders]

Trust me, IT did not get it wrong, you got your sums wrong!

[paulmurr]

speedy_thrills said:

Number = -123

Jumble = -231

Subtract biggest from smallest = -354

Draw a circle around a didget - 35(4)

Type in all number except circled, so 3 and 5.

Says I started with the number "1"?

Genius .

Edited by speedy_thrills on Monday 2nd February 13:00

Doing it wrong mate... -123 is 'bigger' than -231.

[JDMc]

I broke it already...

Picked 1111

[Hedders]

pc.iow said:

Got mine wrong aswell, maybe Hedders works for 7up?

I don't even drink the stuff!

[Hedders]

JDMc said:

I broke it already...

Picked 1111

It does say you need to use a number that has various digits in!

[erdnase]

speedy_thrills said:

Number = -123

Jumble = -231

Subtract biggest from smallest = -354

Biggest = -123
Smallest = -231

(-231) - (-123)
=> (-231) + (123)
= -108

lol, I think?

[elster]

erdnase said:

speedy_thrills said:

Number = -123

Jumble = -231

Subtract biggest from smallest = -354

Biggest = -123
Smallest = -231

(-231) - (-123)
=> (-231) + (123)
= -108

lol, I think?

But it is subtract smallest from biggest.

so -123 - -231
= -123 + 231
= 108

[Hedders]

Why on earth did you decide to use negative numbers if you don't know how to work with them?? :P

[speedy_thrills]

Hedders said:

Why on earth did you decide to use negative numbers if you don't know how to work with them?? :P

It's using a calculator that gets me this time actually, see I added....

[Davey111]

JDMc said:

I broke it already...

Picked 1111

1111 mixed up makes 1111. 1111 - 1111 = 0000. I believe that it says you can't cirlce a 0.

Would love to know the maths to this.

[Hedders]

Davey111 said:

JDMc said:

I broke it already...

Picked 1111

1111 mixed up makes 1111. 1111 - 1111 = 0000. I believe that it says you can't cirlce a 0.

Would love to know the maths to this.

As it happens, i have found it


The trick has to do with divisibility by 9. Try the first part of the
experiment again. Take any number (it doesn't really have to be 3 or 4
digits long, I imagine that's just so the computer has it a bit easy).
Mix up the digits and perform the subtraction.

Now, divide the result by 9. You should come out with a whole number.
In other words, the resulting difference should be divisible by 9.
This works no matter what original number you pick. If you are
familiar with number theory, the proof is simple enough. If not, just
take my word for it that the difference will always be divisible by 9.

So, we have a number divisible by 9. One property of numbers divisible
by 9 is that the sum of the digits of such numbers is also divisible by 9.

For example: 4059 is divisible by 9. 4+0+5+9 = 18. 18 is divisible by
9, so 4059 is divisible by 9.

4057 is NOT divisible by 9. 4+0+5+7 =16. 16 is NOT divisible by 9, so
4057 is NOT divisible by 9.

Let's use 4059 for now. If you pick 5, you enter 409 into the program.
The program adds the digits up: 4+0+9 = 13. It finds the smallest
number that can be added to 13 to get a multiple of 9. In this case 5:

18 - 13 = 5

So, 5 is the missing number.

That's why you are not allowed to pick 0. If the criterion is simply
divisibility by 9, then the program is unable to tell the difference
between 0 and 9.

For example:

4059 --> 459 ---> 4+5+9 = 18

The smallest number that can be added to 18 to get a multiple of 9 is
0. The other number that can be added to get a multiple of 9 is 9
itself. So, both 0 and 9 are possible choices. But since you are not
allowed to choose 0, the program will give you 9.

Try it out. Enter 459 into the machine. It will not give you 0, which
is the number we chose above. It will give you 9 instead.

[Davey111]

Awsome, just freaked out the entire office. THank you

[williamp]

It didnt work with my four didget number: 1000

He guessed 8.