At first glance, Dollar Tree looks like it has some of the best deals on everyday essentials, but some “savings” don’t hold up under unit math. It may look like you’re getting a better price at Dollar ...

Unit pricing makes comparing products—from one brand to the next or between different sizes—more like comparing apples to apples, so it's easier to see which item really saves you the most money.

If you carry a cell phone, you also have a calculator. Pretty much every mobile phone on the market has one, so you have no excuse not to do some intelligent per-unit math while you're out shopping.