Currency conversion - math, yuck

The current rate of currency conversion for Egyptian pounds (LE) to USD is about 1LE = $0.17. So I created a cheat-sheet at home for figuring out the cost conversion, however, despite feeling like I have a grip on things, when I am faced with a shelf of items and have to decide what to buy and what the price is, I go completely blank. I know that when the hawkers yell out that something is “Only one pound,” then it’s only 17 cents, and the metro here is only 1LE one-way, so that’s great, but when in the stores I tend to just stare at the cans of peaches as I try to multiply in the air. (I've finally created a small cheat sheet to keep in my purse that I can casually pull out when I'm shopping, so I don't balk at spending 10LE on a loaf of bread, which is really just about $1.70.) The learning continues...