This is inspired by a problem I read today.
Find 2 9-digit numbers (in base-10 notation) such that one is double the other. Both of them are made up of the 9 non-zero digits once each. 123456789 can be one of them, but 122344566 can't be one of them.
I came up with an answer, but I am not sure if it is the only answer. I had a lot of fun finding it.
Tell me in the comments the 2 numbers you came up with, and what process you used. It doesn't have to be a rigorous proof. It could be a simple investigation based on a particular nice insight(that's what I did)
I'll share my answer once one of you comes up with it and says so in the comments.
(P.S.-For anyone who wants to check out the sources of my problems, Adventures In Problem Solving By Shailesh Shirali and Martin Gardner's 'The Colossal Book Of Mathematics' are awesome to start out with)