Question 11
The diagram shows an addition of a three-digit number, a two-digit number and a one-digit number, with a three-digit sum. The same letter stands for the same digit and different letters stand for different digits. A question mark can stand for any digit, including those represented by a letter. What is the maximum value of the sum?
$$ \begin{array}{r} X\quad Y\quad Z\\ Y\quad Z\\ +\quad Z\\ ?\quad?\quad?\end{array} $$
$$ \begin{array}{r} X\quad Y\quad Z\\ Y\quad Z\\ +\quad Z\\ ?\quad?\quad?\end{array} $$