Related Post: 1 2 X 3 4 X 5 6 X 7 8 1 X 2 X 3 X 4 X 5 X 6 X 7 A=x(x+1)(x+2)(5-x)(6-x)(7-x) 4 2 X )-( X 1 )= 5 6 X 7 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 X9 X 4 5 X 3 6 X 2 7 X 1 8 = 0