Being ranked number one is not a good enough reason

Do not ask for it if the principal can only use adjectives such as "extremely smart", "extremely brilliant ", “smartest student in my career” to describe your student, even if that is the fact. 

Ask for it if the principal knows the student personally and is well aware of specific contributions the student has made to the student body, or a specific trait that stands out among the peers.

Your student is way ahead of the pack. At this early stage, your student has already secured four recommendations, which by itself is no small feat.  By this measure alone, your child is extraordinary.  Your student does not need any more recommendations to prove it.