Mathematics Home Class

"Changing the world takes more than just feeling good. Do we know whether our efforts to save really make a difference? How much plastic do we spare by buying bottled water with slightly smaller caps? When we buy cloth diapers, do we really know whether we’re helping the environment, or whether in fact all that hot water and electricity to wash them cancels out the benefits? We should make sure we are doing good vs. just feeling good. 4. Foreseeing long-term consequences is crucial. This holds just as true for big-ticket items, like the compounding interest on debt. Whether you become a painter, a neurosurgeon or a nail-salon attendant, you will have to manage your finances, and you will survive better if you are willing to fall forward and grasp the numbers behind debt. The 2008 mortgage crisis might have been far less ugly if everyone had had that comfort level. 5. Not all deals are created equal. When people offer you a deal, that deal is probably better for them than for you, or they wouldn’t offer it. Math shines a bright light on this. When you’re pitched a warranty that costs one tenth as much as the product, ask yourself: has one out of every ten things in your house broken before it should have? Those who do quick back-of-the-envelope math skip most warranties, because a few replacements over time will cost little by comparison. 6. You’re not a true grown-up until you know how to tip. It’s incredible how many intelligent, educated adults are afraid to calculate the tip at a restaurant. It just isn’t that hard to divide by five to get 20 percent for a great server, and by 6 to get 16.67 percent for someone less helpful. By the way, women in particular tend to be guilty of ducking the tip task: in my own informal study, it’s running at about 87 percent. Ladies, in begging for help with the tip, we’re failing to convince people — including men — that women are bright, capable, employable people. We also aren’t setting a proud example for girls who look to us as their role models."