A Quad-City-wide scam targeting fast food restaurants is now under investigation, officials from the Bettendorf police said.

"Quick-change" scam artists are targeting mostly Subway restaurants in the area, Lt. Keith Kimball said in a news release. It often happens at shift change or when the restaurant is busy.

According to police, the suspect enters the restaurant and purchases a small low-cost item such as a cookie or a yogurt and then pays with a large-denomination bill, such a $50 or $100 bill. He then attempts to confuse the cashier by changing his mind several times as to how he wants his change back. Or he says he wants to pay with a smaller bill.

By the time the exchange is done, the suspect usually has $20 to $100 extra in cash.

Similar incidents have been reported in Davenport, Moline and Rock Island. The most recent incident happened at the Subway in the 3300 block of West Kimberly Road in Davenport.