The number is in the query. Somebody typing a hire for a hundred is telling you the whole job, and a page that answers whether that quantity exists in stock has done most of the selling already.
Caterers search for depth. Whether four hundred matching plates are available on one weekend is the question, and a company that publishes real stock levels wins the accounts that book every month.
One-off hosts need help counting. How many glasses per person, what to do about spares and which items are actually necessary: those questions come from somebody organising for the first and only time.
Specific items suggest a finished plan. Somebody searching for a particular style of glass or a specific serving dish has designed the table already and needs a supplier who has it.