That's not due to counting "in decimal", it's because of counting in unary: using the number of fingers to represent a number (possible to count from 0 to 10, inclusive), rather than having each finger represent a digit in a number (possible to count from 0 to 1,023 inclusive, in binary).

This was hilarious to write if you're into puns, since the collision between "digit" as in "part of hand" and "part of number" hit me in the face.

If you've got particularly dexterous fingers you could probably count in Ternary and get to 59048, much higher than binary's 1023

hehe good one.

for people that need more info on the joke. You can count with one hand to 31 in binary and to 1023 using both hands.

More info: http://en.wikipedia.org/wiki/Finger_binary