Smarty pants

John was eating some Smarties last night and I told him that if he eats them they will make him smarter.  He didn't believe me so I asked him if he knew what 5 +5 was.  He said no and continued to eat his Smarties.  Halfway through the pack he said, "Wait."  He held up one hand and then the other, spreading out his fingers and said, "5" showing one hand, "and 5" showing the other hand, "is 10!"  I said, "See, those Smarties are making you smarter all ready!  I might just have the smartest nephew ever!