Effective nuclear charge by a 3d electron of Nickel atom (Z = 28)

The expression for the effective nuclear charge Z∗ is
Z∗=Z−S
Here, Z is the nuclear charge and S is the shielding constant.
For nickel Z=28 and S=20.45
Hence, Z∗=Z−S=28−20.45=7.55
Hence, the effective nuclear charge for Nickel atom is 7.55.