Be carefull Killerweed! you have the formula right. But in the USA and Canada the wall voltage will range from 115 to 120, not 125. Then I have never seen a 25 amp breaker used for residential outlets. They are either 15 or 20 amps, almost always 15 amps, It is best to look in your breaker panel and look at the number printed on the breaker to make sure what you have.