How much power is a hair dryer using if it operates at a voltage of 110 volts and has a current of 6 amps?

About 660 watts. A hair dryer has a small blower motor and a resistance winding that heats up. The formula is watts = volts x amps x power factor. In the case of a resistive load like the wire that heats up the PF = 1. However, the blower will have a lower PF of about .8.