Sentence:  Then the horse trading would begin with the words, from the jobber, of: "What's your size?" ... The broker might reply with the word <WSD>"rouf</WSD>" (a 4,000 share trade, which was a very small order); a "score" (20,000); a "monkey" (half a million); or a "gorilla" (one million shares - a very big order). 
Meaning of the word marked with <WSD> tags:  The number four.