Coordination Chemistry and d electron numbers

[ReidMerrill]

Homework Statement

Predict the number of unpaired electrons

[Cr(H₂O)₆]³⁺

Homework Equations

The Attempt at a Solution

I under stand how to fill out the MO with the e_g and t_2g and all but I'm confused about determining the number of electrons.
The answers state this is an octahedral d³ but I don't know why it is d³
Cr is the 4^th element in the d block so it should be d⁴ but since it has a charge of +3 / is missing 3 electrons it should be d¹ but neither of these are correct.

 

[Borek]

Cr has no s electrons?