Answer
Coordination number: 6
Oxidation number: +3
Work Step by Step
The ligands $(NH_{3})_{2}$ and $(NCS)_{4}$ that surround the central metal atom $Cr$ are 2+4=6, therefore the coordination number is 6.
Let us suppose the oxidation number of $ Cr$ is $x$. To find the oxidation number, we sum the known oxidation numbers and equal it to the charge on the complex.
Also,
$NH_{4}= +1$
$(NH_{3})_{2}=2 \times 0$
$(NCS)_{4}= 4 \times (-1)$
The overall charge is 0 on the complex, thus:
$+1+x+0-4=0$
$+1+x-4=0$
$x=+4-1$
$x=+3$
The oxidation number of metal is +3