I agree it's screwy.

Soda is in liters NOW. I'm old enough to remember when the 2 liter was brand new and explaining to my parents that it was about a half cup more than half a gallon.

Funny (in the sense of "peculiar" not "amusing" but while I'm well enough versed in metric I still find myself converting back to approximate US measures when it comes to visualizing how much of something there is or how big something is. Just a matter of what one grows up with and uses most in formative years I think. I'm sure it could be reversed with enough effort but I haven't cared to do that.

I certainly can't multi task like that. I MIGHT be able to do the multiplication, but only if quiet and undisturbed. My wife thinks it's amazing that I can even add, say, three digit numbers in my head, or get very very close to the final price of a basket of goods at the grocery store (if I've been paying attention as we went along) including sales tax. You're talking about a whole different level of mental math. But the US measures are more a matter of memorization than math. Once you've memorized the units, the math is pretty simple - at least, it's simple for me and should be far simpler for you. It's not AS simple as the powers of 10 in metric, but it's simple enough.