21 Everyday Things You Never Knew Even Had A Purpose

What about the hole found in rulers?

Easy. It's for hanging them up.First of all, it’s probably serrated. That might not seem important, but if you’re putting up drywall, it’s pretty huge; the serrated edge lets you easily score softer surfaces, just in case you need to mark a measurement without a pencil.The metal bit also moves back and forth just slightly, which you might have noticed at some point. That’s not shoddy craftsmanship, but rather a compensation for the width of the metal hook.