10.
Thumbs are fingers.
"The English word "finger" has two senses, even in the context of appendages of a single typical human hand:
Any of the five digits.
Any of the five terminal members of the hand, especially those other than the thumb."
Especially, not 'except'
Thumbs can also be known as Phalanges (which surprised me, because I thought that was a made up word for Friends but apparently not...