What is the $EAN$ of $Zn$ in $[Zn(NH_3)_4]^{2+}$?

The $EAN$ of cobalt is $36$ in $[Co(NH_3)_2O_2(en)Cl]$. Thus,$O_2$ is

What is the value of the effective atomic number $(EAN)$ of cobalt in the $[Co(NH_3)_6]^{3+}$ complex,given that the atomic number of $Co$ is $Z=27$?

What is the value of $n$ in the anionic species $[V(CO)_6]^{n-}$ if it follows the Sidgwick $EAN$ rule and has an octahedral shape?

What is the Effective Atomic Number $(EAN)$ of $Cu$ in $[Cu(NH_3)_4]^{2+}$?

What is the Effective Atomic Number $(EAN)$ of the metal ion in $[Cu(NH_3)_4]^{2+}$?