Thanks to all for your replies. Here is some more information.
Ultimately what I need to do is solve a Sudoku puzzle. However, at start, the sudoku is empty so I need to find numbers to fill in the Sudoku in part and then solve it by logic (as you always would solve a Sudoku). So I am trying to find numbers. Most of them I have already found since the answers to the other questions are more science related. For some answers I am quite sure. That is why I know for instance that on position 2 (the second digit) of my ... (unknown number) it can never be a 7 or 8 since that would put my Sudoku in error (i.e. two times an eight in the same row or two times a 7 in the same box). For the first digit, it can hardly be a one, since this would again contradict with a previous answer of which I am 98 % sure. Oh by the way, I am sure I am looking for a number with 3 digits since the question is prased to find 137 153 163 127... (so three dots) but in addition I know the answer gives me three digits for my Sudoku. I agree that in any case many answers should be possible but with the restrictions above, maybe only one true answer is possible. So I am looking for logical OR mathematical solutions to my problem. Hope this helps. Thanks for your brains. Stef.