When I was in high school, I weighed 125 pounds fully clothed and soaking wet. I couldn’t do anything to change it, either. That was the worst part. I yearned to play varsity baseball, but at my weight, I just straight up wasn’t big enough.

College was mostly the same, although I filled out a little. I’d say my average weight in college reflected the “freshman 15,” but for me it was a welcome change.

Then I got a job, spent 4 years sitting on my ass all day, eating large fast food meals, and not getting any exercise. I weigh about 170 now.

So over the years, I’ve put on 45 pounds. Damn. What’s the percent change in my weight from high school to now?

Here’s the general formula for this kind of question:

So plug my values in:

And would you look at that? The percent change in my weight is 36%. Holy balls. I need to go on a diet.

So now say I go on some crazy workout plan, and I lose 45 pounds, so I’m right back where I started at 125. What will be my percent change then? Note: if the answer was just going to be 36% again I probably wouldn’t be wasting your time with this.

Whoa. So it was a 36% gain, but now it’s only about a 26.5% loss? How is that fair? A sorta strange truth about percents (this is true about ratios, too) is that the bigger the numbers are, the less difference a difference makes.

If you’re 16 and your little brother is 13, you’re about 123% his age. But when you were 4 and he was 1, you were 400% his age. The older you both get, the smaller the percent difference will be, but you’ll always be 3 years older than him.

This is also why it’s socially acceptable if your dad is 10 years older than your mom, but it would have been pretty creepy if they met when he was 26 and your mom was 16.

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