[By Bronwyn Collins.]
When trying to solve today's problems about dates, we would have been stuck with out external resources. On the first problem (maybe a link here to the problem?), for example, we knew that one leap year must not have been celebrated between 1896 and 1998, but we didn't know why or which one. Within five minutes of searching the web, we had solved the problem. Some of the other problems required less complicated outside resources, such as a calendar, to get started. It is appropriate to rely on outside resources when you need more facts, when the problem is specific to a real life situation, or when it will simply make your problem solving more efficient. For example, we could have found out what day November 11th 2011 will fall on with out using a calendar, but it would have involved a lot more counting of days. (maybe link to this problem as well?).