I still know the math I learned in high school. I use trig, geometry, and algebra quite often just doing small construction projects around the farm.
I do grounds keeping at a local park and this summer I've been working with a kid who's a junior in high school. He's a smart kid so I try to get him to do some practical math. Like when we were laying out new base placements on the baseball field:
"If the bases are in a 90 foot square, how far is it from home plate to second base?" We double checked that measurement to make sure our layout was square.
Or trying to figure out the amount of fertilizer needed for the grass on the outfield. How would you figure the area involved? He said "I don't know..." I explained, "Well the entire field is a quarter circle with a radius of 360 feet. So figure out the area of an entire circle with that radius and divide by four. Do the same for the radius of the infield and subtract the infield area from the total area".
He knew how to do the math, but had trouble with actually putting it to use in practical applications.