Trivia questions, easily answered by programmers who appreciate the subtleties of time math:<p>1. If someone leaves Vancouver at 1 am and arrives in Seattle at 4 am on the same day, and you know the distance they travelled is 240 km, what was their average rate of speed? (Correct answer: 120 km/h, 80 km/h, or 60 km/h, depending on what day it is. UTC storage helps here.)<p>2. If it's noon in Vancouver, what time is it in London, England? (Correct answer: 7 pm, 8 pm, or 9 pm, depending on what day it is. Knowledge of regional DST schedule differences helps here.)<p>It's my experience that when the programmers get date math <i>correct</i>, they may still find themselves fielding "bug" reports from enterprise customers who <i>should</i> understand the concept but don't (particularly if their business is billing or rate calculation -- think of short term billing for hourly parking or CPU hours as an example).