This morning I ran through the Dunkin Donuts to pick up two donuts for me and two donuts for my wife. Four donuts cost $3.85 while 6 donuts cost a little over $4.00. The cashier tried to convince me that buying 6 donuts would be cheaper. Understandably, the cashier would not know that I was ordering for only two people or that we prefer not to stuff ourselves with more than two donuts each. Still, I feel like the cashier never quite believes that I understand the cost per donut is lower with an order of 6 versus 4 but that it is entirely rational to base decisions on total cost rather than unit cost.