If the value of the US dollar is greater than what I originally exchanged it for, is it considered capital gain? If so, how do I determine the amount I gained?
EDIT: For example, I traded $100 USD for Mexican pesos. I spent some of that money (logically I now have less than $100 USD). But for some reason, the value of the peso skyrocketed so when I go to trade my remaining pesos for USD, I get back $1000.