How much high school math do you actually use in your adult life?

Of all the higher math I learned in high school (and there was a lot of it. All the way through Calculus BC) the one formula I have used the most in my adult life, by far, is calculating ratios.

Tonight I used it to find how many pixels "2 points" is at 300 dpi. Points are the classic measurement for font size from the printing industry, still in use today. But all the conversion charts and conversion sites gave the answer in 72 dpi, which is what a digital screen displays. To find the answer at 300 dpi, I had to set up a ratio and solve for X:

2.67 pixels (2 points at 72 dpi) / 72 dpi = x / 300 dpi

Wheee! The answer is 11.125 pixels. I needed this information for my next T-shirt design, which is coming along. And if my answer is wrong, do please LMK. I need the right info...

I suppose 2nd place in higher math usage IRL would be calculating cubed space. Although once, ages ago, I had to remind my father (electrical engineer) and maternal uncle (aircraft designer) about the Pythagorean Theorem when they were trying to figure out the measurements for a corner shelf in my dad's home office. NGL, I had a bit of fun at their expense. XD