Estimation: the cover area of the math book is 100 square decimeter; The actual length is 20 cm, the width is 10 decimeter and the area is 20× 10=200 (square decimeter). Estimated podium desktop 1.5 m2. The actual length is 1.5 m, the width is 70 cm, and the area is 1.5×0.7= 1.35 (square meter). It is estimated that one side of the pencil case is 2 square decimeters. The actual length is 20 cm, the width is 7 cm, and the area is 20×7= 140 (square centimeter) = 1.4 (square decimeter). It is estimated that the actual side length of the handkerchief is 2.5 decimeters. The area is 2.5×2.5=6.25 (square decimeter). Fill in the form as follows: the estimated area of the handkerchief with the cover of the name math book on one side of the desk stationery box 100 square decimeter 1.5 square meter 2 square decimeter 4 square decimeter measuring area 200 square decimeter 1.35 square meter 1.4 square decimeter 6.25.