Converting Percentage to Number

Converting Percentage to Numberを徹底追究! 知っておきたい トピックの裏側を分かりやすく展開します。

I once bought a “90% effective” air freshener. I thought it would eliminate all the smell of my roommate’s gym socks. I got home, sprayed it, and the room smelled like a damp forest with a hint of foot. I felt betrayed.

If I had converted that 90% to a number, I would have realized it meant 0.9 of the stink was gone. That still leaves 10% of pure, unfiltered sock monster. That 10% is a number. And that number is rude. Percentages promise a miracle; numbers tell you the messy truth.

Converting Percentages | Passy's World of Mathematics

Your Brain is Better Than a Phone

Sure, your phone has a calculator. But using it for every 15% tip makes you look like a robot who can’t handle ice cream. Your brain can do this if you just stop panicking. You are not bad at math; you are just bad at trusting yourself.

Here is a life hack: to find 10% of anything, just move the decimal one spot to the left. 10% of $120 is $12. Done. Now, to find 5%, just cut that $12 in half. That’s $6. Now you can calculate any tip in your head while your friends are still fumbling with their phones. You look like a wizard.