One to change the light bulb.
Four to say that they'd already had the idea for changing a light bulb, but they didn't want to show anyone what they were doing until they'd polished their light-bulb-changing.
Two to point out that someone else had already changed a light bulb, so changing another one was unoriginal and thus not worthwhile.
Three to call light bulbs a new technology that was going to be catastrophic for traditional candlelight-driven writers.
And one to figure out that writers are lousy at math.
I read this joke on Joshilyn Jackson's blog and chuckled so much I had to share.