How old are you?

Lately, Natalie loves to hold up two fingers and tell us "I'm two!"

Here's a conversation we had the other night:

Natalie: (holding up two fingers) I'm two!
Me: That's right. Do you know how old Mommy is?
Natalie: I don't know. Tell me.
Me: I'm 35.
Natalie: Doubting look.
Me: Do you know how old that is?
Natalie: (Looking very concentrated at her hand, holding up two fingers) Two... (Holding up three fingers) Three... (Holding up four fingers, she looked up at me with a Eureka expression on her face) Is this 35?