I am thinking of a 5-digit number. Well, I'm not thinking of it right now, but just go with it, okay?
If you put a "1" at the end of the number, you get a 6-digit number that is three times as big as the 6-digit number you'd get if you put a "1" at the beginning of the number.
In other words, the number _ _ _ _ _ 1 is three times as big as 1 _ _ _ _ _
What is the 5-digit number?