Simply mathematics

E seems to have some fair idea of mathematics though I must confess, I have not been a key contributor towards this achievement.

Me " how many pieces of brownie did you bring to school today?"
E " 3"
Me " if i give you 3 more pieces tomorrow, how many will you have?"

Immediately, he displayed all his ten fingers...and showed me 3 fingers on each hand and started counting and he got the answer!

E "6"
Me " Very good! Since you have 6 pieces, if you give 2 pieces to your friend, how many will you be left with?"

Again, he worked his fingers. This time, he opened up all 5 on 1 side and another finger on the other. Thereafter, he closed 2 and he got his answer!

E "4 but I won't share with them. I will eat it all by myself "

One greedy little piggie, but a smart one!