1. The problem statement, all variables and given/known data Solve the following equations positive integers: (i) a!+b!+c!=d! (ii) a!+b!=25*c! (iii)a!=b^2 2. Relevant equations For the first two one , i have no idea how to begin . But the third one I may use Bertrand's Postulate some where. Could anyone give me some ideas??