The number is usually the style, pattern or color or all three !! That is how china is often ordered by the retailer !! The mfr makes it and the retailer orders by the number !! Much easier to say give me X number of plates, number 303 !! Or X number of 303 coffee sets !! If they didn`t do that how would they describe them out of the many styles they made ?? The number is usually only helpful to the retailer and mfr !!