Establish the amount of yen you wish to convert to American dollars.
Establish the current exchange rate between the yen and the dollar. For example, as of May 12, 2011, a single yen was exchanging for $0.0124.
Multiply the number of yen you wish to convert times the exchange rate to establish the equivalent amount of money in American dollars. For example, you wish to convert 120,000 yet to American dollars so you multiply 120,000 times 0.0124, which equals 1,488, or $1,488.