(1 + 2) × 3 ÷( 4 + 5)=1
1 × 2× 3× 4 - 5 - 6=1
(1 + 2) ÷ 3 × 4 ÷ (5 + 6 - 7)=1
1 + 2 × 3 × 4 - 5 - 6 + 7 -8 =1