I hate that feeling. You learn something so basic that you can’t believe that it took so long to dawn on you.
Like learning how to comb your hair. At age 10.
Or this dang 100% button in the lower right corner of the browser. Did you know that if you click on that it enlarges your window to 125%? Click it again and it bumps up to 150%. But now you’re stuck at 150% right? Nope. Click it again and you back to 100%. So easy. So, why havie I been squinting my ass off half the time?