(20 12? Quanzhou) is a rectangular iron plate, 2.2 meters long and 1.8 meters wide. It should be a circular traffic sign, and the size is shown on the right.

2.2m = 220cm，

1.8m = 180cm，

220÷40=5 (pieces) ... 20 cm,

180÷40=4 (pieces) ... 20 cm,

5×4=20 (pieces).

Answer: it can be made into 20 pieces.

So the answer is: 20.