Also, try not to use the Brazilian bank ATMs as they will charge a high fee AND give you a guaranteed crappy rate (though even the worst atm transaction will only skim ~10 cents off the actual rate which is far better than the 50 cents or more an airport currency exchange will shave off). I consistently find HSBC to be the best as they don't charge a fee and give great rates, often times the exact rate if it's not a volatile day. Banco Brasil once denied my transaction but still debited 500 reais from my account! Thank god I check my statements.