> ENIAC could multiply two, ten digit numbers 357 times per second, and it required 150 kilowatts of electrical power to operate, which works out to about a tenth watt per computation.<p>What am I missing here? A watt is already a rate, joules/sec, so "watt per computation" doesn't make sense. But even assuming they author meant "per joule", the math doesn't work. In a second it could do 357 computations and use 150,000 Joules of energy = 420 Joules per computation.