What is the pms number for the blue in the facebook logo?
The short answer is that there is no corresponding PMS color.
Color in business is intellectual property. Most corporate colors
have their own specific colors which are, in fact, trademarked. If
Facebook used a PMS color, they would be liable to pay Pantone for
the use, I'm an Ink Technician, not a lawyer, so don't ask me how
that plays out in court. Facebook's blue color is as identifiable
as the lower-case "F", and I'm sure anyone contracted to do print
work for them has "Facebook blue" or "Match Blue" written on the
job order.
The closest PMS color in my book is 2727. I would probably
decrease the white to about half of what you'd use to get the
2727.
Hope that helps.