Number of Ahaadith
When Imaam Muslim (rahimahullah) presents a Hadith in his kitaab, his style is that he presents the various chains of the Hadith through which the variations of that particular Hadith may be compared. Hence, through seeing the various chains and wordings of the subject matter discussed or incident explained, one gets a full picture of the Hadith and the full details that relate to the Hadith.
Bearing this in mind, the Ulama have mentioned that the number of Ahaadith contained in Saheeh Muslim, not counting the repetitions, is approximately four thousand. If the repetitions are included, then the number is more than seven thousand. (Sharh-un-Nawawi pg. 21)
Imaam Muslim (rahimahullah) once mentioned, “I prepared this kitaab of authentic Ahaadith from a collection of three hundred thousand Ahaadith which I had personally heard from my ustaads.” (Sharh-un-Nawawi pg. 15)