One, if it knows its own Goedel number.
or
Does it have to be a light bulb? I've got this neat candle holder...
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Because of the bark
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Fifty — one to screw in the bulb and 49 to guard him/her.
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Just one, provided there is a programmer around to explain how to do it.
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Because you better duck when he's pissed.
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They're cheaper than day rates.
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Because he is so cool!
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What's the use, they'd still have bear feet
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Seven. One to change it and the other six to sing about how good the old one was.
or