Learn to Quickly Estimate Foreign Currency Exchange Rates  When
you're out traveling the globe, it's kind of a pain to always be
taking out your cell phone to calculate the exact currency
exchange rate. If all you want is a quick guesstimate, Gadling
offers rules of thumb for converting several currencies into US
dollars.  If you want to know what the exact exchange rate is,
definitely look it up (e.g., at Xe.com). But these rules of
thumb are handy when you just want to roughly know how much
money you're taking out from the foreign country's ATM in US
dollars or whether a tchotchke sold at the market is worth the
price.  The mental math for most countries is pretty easy: in
Belize, divide prices by half, in the UK multiply by 1.5 and
round up, and in Australia and Switzerland no math is necessary
for your estimate (they're roughly 1-to-1 with the US dollar).
Unless you like doing math, however, some countries are more
calculator-worthy (for Colombia, for example, you have to divide
by half, then by 1,000, th