Kindergarten math?

I'm sure I wasn't doing 4-digit addition in Kindergarten, but amazingly, Andrew is. We've been really impressed by the education he's getting at Free Horizon Montessori School, which is a public charter school in Jefferson county. Here are a few of the math problem's he's solved recently.

9222
+ 2999
= 12221

8464
+ 4648
= 13112

Not bad for a 5 year old!