let m, n be Nat; :: thesis: ( not m * n = 485 or ( m = 1 & n = 485 ) or ( m = 5 & n = 97 ) or ( m = 97 & n = 5 ) or ( m = 485 & n = 1 ) )
assume A1: m * n = 485 ; :: thesis: ( ( m = 1 & n = 485 ) or ( m = 5 & n = 97 ) or ( m = 97 & n = 5 ) or ( m = 485 & n = 1 ) )
m divides m * n ;
then ( m = 1 or m = 5 or m = 97 or m = 485 ) by A1, Th24;
hence ( ( m = 1 & n = 485 ) or ( m = 5 & n = 97 ) or ( m = 97 & n = 5 ) or ( m = 485 & n = 1 ) ) by A1; :: thesis: verum