Ksp vavlue

Hi Guys, I'm confused how they solve for Ksp valvue
Ksp = S(2s)^2
= S(4s^2)
Ksp = 4S^3

I don't get the second step how did they end up with S(4S^2)? and what happen to [M]?

Please help

Thanks View attachment 203799 View attachment 203800