David picked up 5 stones.  While some think it was a symbolic reference to the five books of Moses, Genesis through Deuteronomy, others think it was just a practical statement of faith as David was probably preparing to take down Goliath AND his four giant brothers, only needing one stone for each.

And speaking of more than one, heh heh, one of David’s wives was met during his time running from Saul when the king tried to kill David out of jealousy.  This woman’s husband was asked for help, and the guy was so rude that God killed him.  Some time later, David ended up marrying this woman because he admired her wisdom and discretion about the whole situation.  What was this gal’s name?