The first number is the neighbourhood, second is the house, and third is the room. Each of the houses start off with a numbered code - just use that to find the solution you need.
All of these images contain the secret goal as well, and if you don't see it, it means that it's just about getting it done in AS LITTLE MOVES AS POSSIBLE. So any time you hear "quick, fast, on time, and get out of here" don't bother with the extras.