The term 'Number on a Tag' refers to the information that is printed on a tag attached to an item. This tag typically includes the SIZE, PRICE, and COST of the item. SIZE is usually indicated by four letters, such as S, M, L, or XL. PRICE is usually indicated by five letters, such as MSRP or RETAIL. COST is usually indicated by four letters, such as COST or PROF. This information is important for customers to know when making a purchase.