Given the digits 0-9 (10 digits), I was asked how many possible combinations of a 6 digits code can be build. Answer is obviously $10^6$. Then I was being asked further questions, and in order to be able to develop an intuition for this kind of questions, I would like to construct a matrix that will represent all possible codes.
More specifically: thr matrix will provide more information regarding special code combinations, such as the number of codes that contain the digit $0$ exactly once, or number of codes containing the digits $0$ and $2$ at least one.
My question is in what way this matrix should be constructed, meaning what are the cordinates that will cover all $10^6$ possible code combinations.