Students are asked to find all the 3-digit house numbers that satisfy specified criteria. Careful reading of information and understanding of mathematical language are important to finding appropriate solutions. The problem-solving strategies of looking for patterns and establishing an organized list will aid students in finding all possible solutions to the problem. An activity sheet and extensions of the problem are included. This lesson is adapted from an article that appeared in the January 1989 issue of Arithmetic Teacher. (author/sw)