I remember one Saturday morning, my father took me to visit my grandparents, who lived in the countryside and lived mainly by raising ducks. Usually grandparents eat and live in duck farms. When I get to my grandparents' house, I will inevitably look at the duck house and feed the ducks. Duck farm is built along the river ditch, and the other three sides are fences, forming a rectangle. Why don't I build a square to feed my grandpa the ducks? I also said to my grandfather,' Our teacher! When the length of the fence is the same, the enclosed square area is larger than the rectangular area. Grandpa smiled and told me,' What you said is different from what we feed the duck farm. Look at my field. There are ditches on one side and fences on three sides, not all around. Then I naively said,' The ditch is long, why not make it longer so that the area will be larger? Grandpa said, "Not necessarily," Grandpa said, "Pingping, I heard that you have learned to calculate the area of rectangles and squares. I just came to test you today. My duck farm is 40 meters long on three sides. What do you think is the largest area of our duck farm? '

With questions, I fell into deep thought. I used enumeration method to infer: suppose the width is 1 m, the length is 38 meters and the area is 38 square meters; 2 meters wide, 36 meters long and 72 square meters in area. List step by step ... width10m, length 20m, area 200m2; Further down, the area is gradually calculated and the area is gradually reduced. In addition, I cited other figures to prove it and see what the characteristics are. I explored such a rule. In this way, the area of a rectangle surrounded by a river on one side is larger than that of a square. It is not that the longer the area is, the larger the area is, but that the sum of the two wide areas is the largest. With the joy of success, I said to my grandfather,' Grandpa, you tested my question, and I thought about it for a moment, but I didn't.

From this example, I feel that in real life, only rational and scientific use of resources can bring the greatest benefits. From this, I also think that mathematics will bring wisdom and create wealth. It can be said that there is mathematics everywhere in life, and it is inseparable from mathematics everywhere in life.