how do you convert power "P" into kWh?

eg. Plasma TV power = 210W

how do i make that to find its usage in kWh assuming it was on for only on for 2 hours?

thanks.
2009 Engl Powerball 100watt
1985 Marshall 1960a 4x12 with G12-65s
1989 Ibanez 540S LTD DY
2006 Epiphone G-400
gah bump
2009 Engl Powerball 100watt
1985 Marshall 1960a 4x12 with G12-65s
1989 Ibanez 540S LTD DY
2006 Epiphone G-400
210 Watts = 0.21 kWh, multiplied by 2 = 0.42 kW total
accually thats what i got but then that just doesn't make sence in the end when you're charged \$0.045/kWh
2009 Engl Powerball 100watt
1985 Marshall 1960a 4x12 with G12-65s
1989 Ibanez 540S LTD DY
2006 Epiphone G-400
Last edited by acdc51502112 at Jan 8, 2007,
A kilowatt = 1000 watts... so you take the number of watts and divide by 1000... now you have the number of Kilowatts/hour. So multiply the number by 2, because it was 2 hours.

EDIT: to find your charge, take the number of kilowatts and multiply it by the price of kW/h
thx m8
2009 Engl Powerball 100watt
1985 Marshall 1960a 4x12 with G12-65s
1989 Ibanez 540S LTD DY
2006 Epiphone G-400