{\displaystyle S={1 \over \,5\,}\;V\;\left[1+{1 \over \,10\,}\log _{10}(V)\right]={1 \over \,50\,}\;V\;\left[10+\log _{10}\left(V\right)\right]={1 \over \,50\,}\;V\;\left[\log _{10}\left(10^{10}\right)+\log _{10}\left(V\right)\right]={1 \over \,50\,}\;V\;\log _{10}\left(10^{10}\;V\right)}