That's exactly right.Hi,

I will have to check this with a computer program in( VB.Net )Visual Basic.Net

It seems that as 13 times 11 times 7 is 1001

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.so maybe all numbers of the form XYZXYZ like 123123 are divisible by 1001

If that is TRUE that is the reason it works.

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