I think it may have been someone on this website who recommended looking at the pbs website to see detailed lists of what's "normal" math skills.
http://www.pbs.org/parents/childdevelopmenttracker/two/mathematics.html

Sure doesn't seem "normal" to me but what do I know.

My DS2.4 is not doing much mathy stuff yet though rote counting under 100 seems easy for him and reading/recognizing numbers below 1000 also. Can add by ones under 10, but not subtract, and thinking about plus 2 or 3 seems to turn on his guessomator. Is able to one to one count but doesn't seem to have the patience for it, likes to guess.

Polly