Nodding about Numbers

One of Sophia's newest developments is the copious nodding you see in this video. I don't know if she's picked this up from someone--i.e., do I nod a lot?--or if it's just her own unique thing, but she's been doing a lot of serious nodding lately, letting us know when she agrees with something.

P.S. Five seems to be Sophia's favorite number at the moment.