PASADENA, Calif. -- The number of bogus bills in circulation is growing, the Los Angeles Times reports. The Secret Service removed more than $182 million in fake U.S. money from circulation for the fiscal year ending September 30, 2009 ?" more than twice the amount during the previous fiscal year.

Counterfeiters tend to target cash-based businesses, such as convenience stores, gasoline stations, quick-service restaurants and small grocers, to pass on their funny money. Increasingly, fake bills are cunningly designed and difficult to discover with an untrained eye.

At Pasadena??s Union 76 station, manager Valod Mehrabian uses his intuition and a small machine to detect the real from the fake. Typically, he??ll rub the bill to see if it feels real before running it through an ultraviolet light machine designed to show the thin line of fluorescent polyester thread present in legal currency.

Experts say untrained clerks at small businesses often unwittingly accept counterfeit bills. Teaching cashiers how to detect a fake bill is one of the most effective ways of not getting scammed by counterfeiters.

In April, the federal government revealed its redesigned $100 bill, which has color-shifting ink and 3-D images on plastic strips. The new design will debut in February. The most commonly faked paper currency in the United States is the $20 bill.