One of my kids is an astronautical engineer. We homeschooled him so when he was a senior in high school he took a few community college classes to get acclimated to institutional education.
He bombed the math entrance exam. He’d kind of forgotten the basic math because he’d been doing advanced math.
A friend has a masters in some sort of very obscure mathematics. When she began homeschooling her kids she realized she couldn’t do math with numbers. All her knowledge was formulas and symbols.
I keep current with percentages and fractions because my wife is always asking me to figure sales discounts.
For 18 years Calculus was used daily in my field of weapons work. All of us would rely on a stupid calculator to do the simple math because we had nearly forgotten how to perform it while ding all the higher stuff.