Margen
In 2009, researchers from Cornell's hotel school ran a test at St. Andrew's Café, the restaurant of the Culinary Institute of America. They printed three menus identical except for one detail: prices appeared as "$20.00", as a bare "20", or written out in words. Guests who got the symbol-free menu spent around 8% more than the rest.
The explanation ties into the "pain of paying": a currency symbol reminds you that the number costs you money. Remove it and the price becomes a neutral figure, and the brain lowers its guard. We order with our appetite, not our wallet.
Look closely next time you eat out: in many restaurants, especially expensive ones, prices carry no symbol, no decimals, no neat right-hand column. "Sea bass 24". None of that is accidental.
The antidote is simple: put the symbol back yourself and read the full price. The moment 24 becomes 24 euros again, the spell loses its power.