The EAN of Cr in [Cr(CO)6] is: (Cr atomic number = 24)
Cr is in 0 oxidation state with 6 CO ligands. EAN = 24 − 0 + 2 × 6 = 36.
Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Colour and Magnetic Properties and Stability and Importance