Zhivete stands seventh and writes zh, the voiced palato-alveolar fricative. Its name is a Slavonic imperative plural meaning live. It carries no numeral value.
The absence of a number is the diagnostic. Greek had no letter for this sound, so there was no Greek numeral attached to any sign that could be borrowed for it, and the letter takes its place in the alphabetical order without taking a place in the arithmetical one. The same combination, a shape with no Greek model and a letter with no Greek number, holds for tsy, cherv, sha and shta, and those five letters together are the clearest evidence of where the borrowed Greek alphabet ended and the work done for Slavonic began.
The sound itself is thoroughly Slavic. It arose from earlier palatalisations, it is common, and no Slavic language has lost it, which is why the letter has survived in every Cyrillic alphabet in use today with its shape essentially unchanged. It is symmetrical about a vertical axis, which is unusual in this script and has attracted comment for as long as anyone has been comparing letterforms.
In the church books it needs no special rules: unlike the pairs of letters that write one sound, zhivete has no rival and no orthographic distribution to learn. It is one of the small number of Cyrillic letters that has only ever meant one thing.