I’ve been pretty successful selling t-shirts on Amazon these past few months. I normally only sell one, maybe two shirts per order, but one particular order caught my eye. I sold eight of these Euler’s constant t-shirts on January 15th. Cool, easy money. When February 7th rolled around, Wikipedia shared on their Facebook page that it was Euler’s Constant Day.
Should you buy LED bulbs? What about replacing an old vehicle with a more fuel-efficient vehicle? When exactly is an energy efficient upgrade worth the investment? While part of these questions has environmental and safety considerations - making the answer a definite “it depends” - the financial aspects are a little more straight-forward. Essentially the answer is “yes” if the item - LED bulbs, a car, or what have you - pays for itself in a certain time frame.