My 6yr old did similar things when he had just turned 2 or a few months before. He's not been tested yet but I didn't think it was "average" at the time. I was changing his diaper, about 20months old, maybe 22months, and he had a cookie in his hand. He asked for another cookie. I asked him if I gave him another, how many would he have. He said, "2." I asked, what if I gave you two more cookies, how many would you have? He said 3. I said, what if I then gave you two more cookies, how many would you have and he said 5. I then said if you eat 1 cookie, how many would you have? He said 4. I asked if he then ate 2 of his cookies, how many would he have and he said 2. It was all done in his head w/out manipulatives.

Dazey