Change money in the street
Never accept to change money in the street. Even someone offers you a good changing rate there is a chance that: 1 - You gonna get some fake bills mixed with the real ones and since you are not used to the Brazilian money you will not be able to detect that. 2 - Some of these scammers use rigged calculators so even if they give you real Bills that calculator is programmed to show a number that is smalls then the one you should get. So always use just ATM or official money changers.