let m, n be Nat; :: thesis: ( not m * n = 626 or ( m = 1 & n = 626 ) or ( m = 2 & n = 313 ) or ( m = 313 & n = 2 ) or ( m = 626 & n = 1 ) )
assume A1: m * n = 626 ; :: thesis: ( ( m = 1 & n = 626 ) or ( m = 2 & n = 313 ) or ( m = 313 & n = 2 ) or ( m = 626 & n = 1 ) )
m divides m * n ;
then ( m = 1 or m = 2 or m = 313 or m = 626 ) by A1, Th25;
hence ( ( m = 1 & n = 626 ) or ( m = 2 & n = 313 ) or ( m = 313 & n = 2 ) or ( m = 626 & n = 1 ) ) by A1; :: thesis: verum