How many men did the squire want for the crew of the Hispaniola in Treasure island?

The famous novel Treasure Island by Robert Louis Stevenson tells of a thrilling hunt for pirate treasure based upon a map that Jim Hawkins and his mother acquire from a pirate in hiding named Billy Bones. After learning of the map, Squire Trelawney outfits a ship, the Hispaniola, to search for the island and the treasure. The squire details how many men he wants for the crew in a letter to Dr. Livesey about the progress of his preparations. He writes: "I want a round score of men - in case of natives, buccaneers, or the odious French..." In other words, he wants exactly twenty men so that the ship will be sufficiently protected during the voyage.

Unfortunately, Squire Trelawney happens upon the notorious one-legged pirate Long John Silver and hires him as cook. Silver promptly fires some of the men that Trelawney has already found, and fills the ship with pirates like himself who will eventually mutiny and threaten the lives of all aboard. Trelawney writes:


Between Silver and myself we got together in a few days a company of the toughest old salts imaginable - not pretty to look at, but fellows, by their faces, of the most indomitable spirit.


In addition to the regular crew, Dr. Livesey becomes ship's doctor and Jim Hawkins becomes the cabin boy.