Laura Laing graduated from James Madison University with a BS in Mathematics. After teaching high school math for four years, she became a staff writer for Inside Business. Her articles have appeared in Parade, Parents, American Baby, The City Paper, Baltimore Sun, and The Advocate.
Unless you just hit the Lotto jackpot, you’re probably looking for ways to save a little cash at the register. Whether you’re buying groceries or the perfect knickknack for your newly decorated living room, keeping more money in your wallet can be a real challenge. The key is to plan ahead and stay sharp.
Estimation Is Your Friend
What’s more important: finding your server’s tip to the penny or getting out of the restaurant with your sanity intact? We all know some of those folks who obsessively use a calculator to find the tip on their morning bagel and coffee, but how much fun are they? (And how much fun are they having?)
When you estimate, you create math problems that are simple to solve in your head. You round numbers so that they’re easy to add, subtract, multiply, or divide. You evaluate what you can do well and apply those strategies to the problem at hand. In short, you look for ways to do mental math.
But you are not guessing. In some instances, you’re finding a range of possible solutions that make sense. In other situations, you’re merely figuring out the answer to a yes-or-no question. (Can I afford to buy those designer shoes?) And sometimes you just don’t need to have the answer down to the penny. (How much can I expect to pay each month for my mortgage?)
Mathematicians and scientists estimate all the time—even when they’re looking for an exact answer. Estimating helps you judge your solution, and this in turn can keep you out of embarrassing situations (like arriving at the party way too late) and hot water (like paying more than you can afford for your not-so-smart phone).
Estimation is one of those nifty skills that can help free up your brain for the important stuff—like remembering your debit card PIN or where you parked your car. When you estimate, you don’t get bogged down in unnecessary details.
Look, there are going to be times when you need to do some mental math (figuring out whether a “Big Sale!ˮ means you really can afford that new jacket) or scribble some calculations on a piece of paper (cutting a recipe in half). But if you want to use a calculator, go right ahead. If you need to call your dad for math help, have at it.
Predicting what you can save over the next year is a bit like developing a weather report. You might have some good models and some past data to base your forecast on, but in the end, just about anything can happen.
So if you’re looking for a sure thing, look elsewhere.
Let’s say you’ve estimated that you will save $300 a year by brewing your morning cup of Joe instead of buying it on the way to work. But so many things can affect those savings. If you have to replace your $200 coffee maker, you’ve seriously eaten into your surplus. And if the coffee shop introduces a club card that can save you big bucks, you might just be better off stopping there in the A.M.
And then there is the value of your time. You can calculate this using your hourly salary, or you can use your own logic. Does it take you 3 hours a week to save $150 clipping coupons and researching grocery sales? If your hourly salary is $100, the savings may not be worth it.
Then again, they may be.
Math can be flexible and useful. But it won’t tell you what you must do. That’s because math is both a tool and a language. It facilitates a process and explains why something works. So calculate your little butt off. Just remember that you—not the numbers on the page—make the final decisions.