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## 'Repeaters' printed from http://nrich.maths.org/

*Tim
from Gravesend Grammar School sent in this solution.
Well done Tim.*

Let the original number chosen be n.

The new six digit number formed is made by adding n to n shifted
three digits to the left, ie 1000n, so the new number is 1000n + n,
or 1001n. 1001=7*11*13, so 1001n will always have the factors 7, 11
and 13