“退”是一种重要的解应用题的策略。解某些数学题,常常需要“退”,“退”是为了“进”——解题。著名数学家华罗庚指出:“善于‘退’足够地‘退’,‘退’到最原始而不失去重要性的地方,是学好数学的一个诀巧!”(引自《数学归纳法》一书)而解题是数学学习的重要部分,可见“退”这种思想方法的重要性了。用“退”的思想来解题,应当从小学低年级就进行渗透。但有些 “Back” is an important strategy to solve the problem. Solve some math problems, often need to “retreat”, “retreat” is to “enter” - solving problems. Hualang Geng, a famous mathematician, pointed out: “Being good at retreats' enough to 'retreat' and 'retreat' to the most primitive place without losing importance is a trick to learning mathematics!” (Quoted in Mathematical Induction ) Solving problems is an important part of mathematics learning, showing the importance of “retreat”. To solve problems with the idea of ​​“withdrawing”, we should infiltrate the lower grades of primary school. But some