“Mom, stop being a teacher!” is one of Amigo’s favorite taunts. He uses it when I’m, well, trying to teach him something he can use in real life. Some of these skills might come in handy. I swear it.

Today’s topic: Math. Math skills in the big bad world outside of a classroom. I encountered three examples recently that were all money skills: adding up a total, making change, calculating a tip, and figuring out a unit rate. Oops, that’s four. Sorry.

At the farmers’ market, the young woman was a little frazzled from the busy sales on this nice warm day. I needed two pounds of sugar snap peas and two pounds of green beans. She weighed out the vegetables, and then she stopped. “How much? Um, wait a minute.” She reached for a pocket calculator. “2 times $2.75 for the peas, $5. 50. 2 times $3.50 for the beans, $7.” Then she needed a total. “$5.50 plus $7 is $12.50. Right?” She looked to me for confirmation. I nodded and handed her a $20 bill.

Now in a classroom, I’d have the students count up first. $12.50 plus 50 cents is $13. $13 plus two is $15, and five more make $20. They would then hand the customer a five, a one, and two quarters or some other variation of $7,50. But I made it harder – or easier – by handing her a $20 bill and two quarters. Oh, no! I changed the problem! The buzzing and busy young woman figured it out by using her calculator, and I smiled as I double checked my change.

Class, I mean readers, we’re at two skills now: total and change, involving multiplying, adding, and subtracting.  Be it farmers’ market, garage sale, or lemonade stand, these are necessary skills. Put them in your business plan.

Tips. Folks, I’ve been a waitress. I wasn’t a very good one. I appreciate a server’s hard work, and I tend to tip high rather than low. Here’s an easy way to figure out a standard 15% tip. When your calculations are done, I recommend you round up. Your server most likely earned it.

• Step one: look at the bill’s total.
• Step two: multiply by 10% by moving the decimal point one place to the left. For example, 10% of a $30 check is $3.
• Step three: find half of the ten percent quantity. Using the above example, half of $3 is $1.50.
• Step four: Add ten plus five percent to find fifteen percent. $3 + $1.50 = $4.50.
• Step five; If you’re like me, and I hope you are, round up. A $5 is appropriate in this instance.

Did we have one more math application? Oh, unit rate. Unit rate is a ratio expressed as a comparison of two unlike quantities. Huh? Think miles per gallon, ounces per price, pounds per unit price. The goal is to find out how much relates to one, and then compare to find the better deal. Some grocery stores do this for you on the shelf tags. Read them. The bigger sign isn’t always the better deal.

The best deal is recognizing a deal when you see it. Whether it’s shoes (20% off the clearance price for my new black Mary Janes) or produce, math is a real-life skill. Now I’m going to go measure tomatoes for salsa. Oh – measurement and proportion! Here we go again!