Pop math quiz: Arubian currency exchange is 1.75 Arubian florin = 1 U.S. dollar. Gasoline is sold by the liter. So, here's the fuel we just put in the rental car. Is the price on this pump pricey or cheap compared to the U.S.?
I can do metric system in my head. I can convert currency in my head. What I can't do, is two-step conversions like this one, in my head. Last time I tried I ended up paying $12 for a pineapple in Barbados!