The oxidation number of ‘Mn’ in $KMn{O}_4$  is

In $KMn{O}_4$ , there is one potassium atom, 1 manganese atom and 4  oxygen atoms are present. The oxidation number of Mn in $KMn{O}_4$  is calculated as below:

${\text{KMnO}}_4\Rightarrow \text{1}\left(\text{K}\right)\text{+1}\left(\text{Mn}\right)\text{+4}\left(\text{O}\right)\text{= 0}$

$1\left(+1\right)+1\left(x\right)+4\left(-2\right)=0$

$x=8-1$

$x=+7$ . Here x is oxidation number of Mn

$\therefore$  Oxidation number of ‘Mn’ in $KMn{O}_4$  is $+7$ .