Sorry state of math skills
McDonalds last night.

G: That will be $3.18
M handing the guy a $5: I've got the 18 cents
I dig in my pocket and start to hand him the 18 cents
G bewildered look on his face as he points to the register which states the change as 1.81: Oh... you have the change? Well can I just give you the 81 cents?
M: No, just give me $2 back
G enlightened happy look on his face: Oh... ok