Corrected On sequence nXn where x equal 09,18,27,36,45,54,63,72,81,90

[Pieter Moree]

Ed Pegg wrote:

> These are ten numbers in arithmetic progression.
>
> At least one of these numbers will be divisible by 7.

This is true, provided the common difference is not divisible by 7.
The common difference here is of the form 9*10^k where k is the number
of digits of n. This is never divisible by 7 and hence at least
one of the numbers is divisible by 7.

Pieter Moree