There are six different 6-digit positive integers that add up to a seventh 6-digit integer. Interestingly, all seven of these numbers consist of combinations of only two different digits. That is, only two different digits are used to write the complete set of seven numbers--the same two digits in each number.
So far you can't deduce what the numbers are, but if I were to tell you that seventh number, that is, the total, you'd know what the other six numbers were that made up that total.
What are the seven numbers?
From Enigma No. 1702, "All the sixes",by Ian Kay, New Scientist, 16 June 2012, page 32.
The fact that the text, although improved by Charlie, comes from "New Scientist"'s Enigma does not make it immune from my revision and appropriate conclusions.
And again, I LIKE THIS PROBLEM.