Fair enough regarding the washer/dryer, but I'm unimpressed by the hammer/nail example. If anything, I might want to buy "some nails" rather than "a nail", but I would argue that's not a brilliant guess either—if I'm buying a hammer I most likely already own the item that I want to hit with it. Some more interesting suggestions could have been for example "some pliers", "a set of screwdrivers", "a pair of work gloves", "safety goggles", etc.