It depends. Depends first on what you consider a "Cpmp". As the saying goes, "every comp is a sale, but, not every sale is a comp". The number is less important than whether or not you have chosen the most similar, most proximate, and most recents sales as comps. And it further depends on what the market activity is in the subject neighborhood and market. If it is a well defined neighborhood with similar properties to the subject, with similar square footage, style, age, amenities, and financing, and are recent sales, then the numbers may change to accomodate that. If there were only 10 sales and only 4 met this criteria, then 4 would be a good indication of the market. if it is a rural area, few similar sales, and many miles in between the closed sales, then it may require a different amount to get a true sense of the market.