Number of stable digits of any integer tetration

In the present paper we provide a formula that allows to compute number of stable digits any integer tetration base \in {\mathbb N}_0. The digits, at given height power tower, indicates how many last (generic) are frozen. Our is exact for every which not coprime 10, although maximum gap equal V(a)+1 (where V(a) denotes constant congruence speed a) can occur, in worst-case scenario, between upper and lower bound. addition, a>1 multiple show corresponds 2-adic or 5-adic valuation a-1 a+1, even order a^2+1, depending on class modulo 20.