1. The bowling radius is about 1dm, and the fairway length is about 18m. How many times should bowling be rolled from one end to the other? 2. A circular iron ring with a diameter of 40 cm. How long does it take to make such an iron ring? 3. Acrobats perform tightrope walking on unicycle. The diameter of the wheel is 40 cm. How many turns does a 50-meter-long steel cable take? 4. Xiaodong measured that the circumference of the thickest part of a tree trunk is 125.6cm, and what is the cross-sectional area of the thickest part of the trunk? 5. Cut a circular piece of paper into a myopic rectangle with the same width and radius and the same area. The circumference of this rectangle is 16.56 cm. What is the area of the cut circular paper? 6. Draw a circle with a circumference of 12.56 cm, the distance between the two toes of the compass is () cm, and the area of the circle drawn is () cm 2. 7. Cut a piece of cardboard with a length of 8cm and a width of 5cm into a small disc with a radius of 1cm. How many small plates can you cut at most? 8. In track and field competition, the throwing circle of shot put is a circle with a diameter of 2. 1 m, and the throwing circle of discus is a circle with a diameter of 2.5 m.. How many square meters is the area of discus throwing circle larger than that of shot put throwing circle? 9. Xiaohua measured that the area of a round desktop is 3.768 meters. How many square meters is the area of this round desktop? (The number shall be kept to two decimal places) 10. A circle with a radius of 4, draw a circle with a radius of 4 at any point on the circle and find the area of the intersection.