How many worms do I need?

We were at dinner with some new friends last night. I was asked how many worms does one need, to start composting. The quick answer is a minimum of "2".  At the NCSU Vermiculture conference in 2012 the research suggests starting with 1 pound (500-1,000) red wiggler worms in a bin no deeper than 3 feet. Adding more worms equals more efficiency. For those of you wondering about placing worms in your garden bed, the recommended suggestion is 4 wigglers per square foot.