The size of ordinary stamps in China is not absolutely fixed.

Small ones are 23.5 mm * 16.5 mm (387.75 mm2 (3.8775 cm2)), and commonly used ones are 30 mm *40 mm (1200 mm2 (12 cm2)) and 22*27 mm (594 mm2).

Extended data

The range of common objects in life

1, pencil case: about 20 cm long, about 10 cm wide and about 2 square decimeters in area.

2. Math book: about 20 cm long, 15 cm wide and 3 square decimeters in area.

3. Exercise book: about 25 cm long, 20 cm wide and 5 square decimeters in area.

4. Examination paper: about 40 cm long and 30 cm wide, with an area of 12 square decimeter.

5. Desktop: about 60 cm long, 40 cm wide and 24 square decimeters in area.

6. Classroom door: about 2m long and 1 m wide.

Area: about 2 square meters

7. Blackboard surface: about 4 meters long.

The width is about 1 m.

Area: about 4 square meters

8. Classroom floor: about 8 meters long and 6 meters wide.

Area: about 48 square meters

9. School playground: It is about 100 meters long, 50 meters wide and covers an area of about 500 square meters.

10, the area of a nail is about 1 cm2; The area of a palm is about 1 square decimeter; The four floor tiles in the classroom are about 1 m2; The area of the dining table is about 1 m2.

1 1, Yuzhong District covers an area of about 22 square kilometers;

Chongqing covers an area of about 80,000 square kilometers;

China covers an area of about 9.6 million square kilometers: