I've worked in EMS for years and found that different cities do different things. But when searching for houses I have found that the street numbers do not always run in order. Especially if there are spaces or gaps between the current structures. They leave out numbers in case someone decides to build another structure in between existing stuctures.

Your local Fire Dept or EMS agency are great sources for info. Or just call the Police and tell them that it is the house accross from XX and give a description of the house that you want to report. You can also try to catch the mailman and ask them what the address is. Good Luck!