I'm 28. I want to re-learn maths. I don't have a college degree and work full time as a sysadmin with lots of downtime. I realized I haven't done much math since high school and even forgot how to do long division until I looked it up.

Basically, if you were a brainlet that wanted to relearn math, how would you go about it? Should I just order some pre-algebra, algebra, geometry, trig, and calc text books or is there a better way?