Here's how I'm converting Czech korunas into U.S. dollars here in Prague:
1. Find the koruna price.
2. Remove the last two digits.
3. Divide the remaining figure by four.
4. Sense I've done something wrong. Scratch head.
5. Start again with the full price.
6. Remove last two digits.
7.
Multiply that figure by four.
8. Scratch head again as I realize that while I'm pretty close to the dollar price, I'm still off by a few bucks.
9. Shout out, "Hey Britt, how much is this in dollars?"
10. Britt effortlessly divides the koruna price by 23.7 in his head, as he is a super-genius at math, and then he tells me the answer.
My system is working pretty well so far. Well, everything except steps 1 through 9.