> > The right thumb is the half-carry bit.  Though if there's no use for base 10
> > I suppose half-carry isn't all that useful...
> >
> > Actually, I personally usually use my hands to count to 100: the ten digits
> > have values:
> >   10 10 10 10   50       5    1  1  1  1
>
>  Why stop there? Goto 1024.
>
>    512 256 128 64  32    16  8 4 2 1
>
>  hummm, where have I seen that before.

The problem is that human physiology does not allow all 1024 states to be
represented with equal ease.  Assuming that a bent figure is "low" and an
extended finger is "high", even counting up to two is hard; 10 and 26 are
horrible [25: thumb, index finger, and pinkie are extended.  To go to 26,
bend the pinkie while extending the ring finger.  On most people's hands,
this is very awkward.]

By contrast, the base-100 scheme above allows the fingers to be extended in
easy sequence (index finger first), and the only combined bend/extend move
is extending the thumb while bending everything else (easy).