##### Technical Math For Dummies

Calculating a 15-percent tip in your head may seem tricky, but here’s a, well, tip for those situations when you need to calculate that standard tip amount. And it works 100 percent of the time. In order to determine a 15-percent tip, follow these steps:

Just move the decimal point one place to the left. For a \$50.00 dinner, that’s \$5.00.

2. Figure half of the amount created in Step 1.

Half of 10 percent is another 5 percent. In this case, you get \$2.50.

3. Add the amounts from Steps 1 and 2.

Together they’re 15 percent of the bill. So \$7.50 (\$5.00 + \$2.50) is a 15-percent tip for a \$50.00 dinner.

Many cellphones and smartphones have tip calculators, but the steps provided here can help you out in a pinch if you don’t have access to your phone for some reason.

Barry Schoenborn is a technical writer who has worked in many of the trades described in the book.

Bradley Simkins has taught numerous classes and tutored at the Multimedia Math Learning Center at American River College in Sacramento.