This applet provides an opportunity to pose questions that have more than one correct answer. If one of the numbers - top, bottom or sum is hidden, then clearly there is one correct solution to the problem. If two of these numbers are hidden - there are many solutions to the problem. How many? If selected digits are masked then each problem has a finite number of correct solutions. Can you find a solution? How many solutions can you find? How do you know you found them all? [b][i]Best viewed as a Java applet[/i][/b]