[chm]

    For example, the largest unsigned binary 64-bit ­integer—18,446,744,073,709,551,615—
    could be held in 20 bits instead of 64.

This should read "could be held in 20 digits instead of 64 bits."

[jlangenauer]

If "bit" is a portmanteau of "binary digit", wouldn't the analogue in a senary[1] number system be a "sit"?

[1] http://en.wikipedia.org/wiki/Senary