Customers who split the bill at the Cheesecake Factory and pay the suggested gratuity have been duped, a new class-action lawsuit against the California-based restaurant chain alleges.

The restaurant calculates the suggested gratuity based on the total bill, not each diner's share, according to the complaint. Many customers who were too distracted, drunk, or indifferent to bother to do the math themselves and used the suggestions as a reference have unintentionally left tips that were a much greater percentage of their check than they believed.

In the lawsuit, the plaintiff's share of the bill was $38.50, and the suggested gratuity printed on the receipt ranged from $11.50 to $16.94. These gratuities, however, were based on the total bill before splitting, not just the plaintiff's share. So in fact, $11.50 is about 30% of $38.50, and $16.94 is 44% — not 15% and 22% as printed on the split bill.

The plaintiff, Marcel Goldman, left a $15.40 tip, which is suggested on the receipt as a 20% tip, but is actually 40% of the split bill. Although Goldman later sent a letter about the "billing error" to Cheesecake Factory's headquarters, she said that the error was not corrected.

"Consumers should be aware," Goldman's attorney Julian Hammond told BuzzFeed News. "Why are we left to our own devices to do arithmetic acrobatics when the suggested gratuity represented is not true? The mathematic calculation is misleading. It must end; it needs to change."

