# Another math trick

#### Mark44

Joined Nov 26, 2007
628
Hi,
I will have to check this with a computer program in Visual Basic.Net ( VB.Net )

It seems that as 13 times 11 times 7 is 1001
That's exactly right.
so maybe all numbers of the form XYZXYZ like 123123 are divisible by 1001
If that is TRUE that is the reason it works.
Yes, that's why it works, and I think this was explained earlier in this thread. You won't be able to prove this relationship with a computer program; all you can do is to confirm it with a number of examples. The way to prove the relationship is on paper by using algebra.

If you take any three-digit number and multiply it by 1000, you'll get the same three digits followed by three zeroes. Add the three-digit number and you'll get the same three digits you started with followed by the same three digits.
Mark

#### DrMarten

Joined Aug 11, 2008
5
That's exactly right.

Yes, that's why it works, and I think this was explained earlier in this thread. You won't be able to prove this relationship with a computer program; all you can do is to confirm it with a number of examples. The way to prove the relationship is on paper by using algebra.

If you take any three-digit number and multiply it by 1000, you'll get the same three digits followed by three zeroes. Add the three-digit number and you'll get the same three digits you started with followed by the same three digits.
Mark
Hi,

You can prove it with a computer program that every number from 100 to 999 will work though.
Mathematicians often use computers to run a test through a series of numbers, whether the numbers are consecutive or not though depends on the theory being tested.

Run a loop from 100 to 999
Join each number together so you end up with the numbers

100100 to 999999 in a STRING

convert the STRING back to a number and divide each of those numbers by 1001

Written algebraic proof is better though, I think. ;-)

Of course computers are just machines that are full of transistors or switches, in other words a computer is as thick as any wall!! It is computer code that makes all the things a computer can do today.

Regards,

DrM

#### myidismine

Joined Oct 22, 2008
4
curiosity is a sign of intelligence. If a person shows no curiosity for something he has not seen or experienced before, you must consider him/her unintelligent.

On the oder hand, it is very difficult to impress very intelligent persons with very high level of education. The reason is they have read, seen, observe and experience with so much;therefore if you try to impress them with something so simple as a cheap arithmetical trick, they will not be impressed. Very often they have seen it somewhere already.

It is as if you are trying to make someone laugh with a joke he already heard.

myidismine,

#### thingmaker3

Joined May 16, 2005
5,084
It is as if you are trying to make someone laugh with a joke he already heard.
Just because you've heard it does not mean everyone else in the audience has.