900÷30 12×40 480÷80 16×6 12×7

420÷60 100×26 2400+300 5600÷70 320+780

90÷ 18 16×25 480+30 300-25×4 100-72÷8

689×5≈ 5430÷9≈ 3976÷8≈ 2080×4≈ 260×8≈

2, vertical calculation and checking calculation:

209×43 8652÷36