九年义务教育三年制初中《代数》第一册(上)第38页,B组第二题为:正整数从1开始,逐个相加,一直加到n,它们的和记作s,即s=1+2+3+…+n(n表示一个正整数),写出计算s的公式.这道题目中含有字母且设问富有思考性,解题方法体现了数学方法,更重要的是结果能作公式用,而且应用分层次用.为帮助同学理解这些特点,现对这道题进行解读,供同学们参考. Nine years of compulsory education three-year junior high school algebra Volume I (on) p. 38, B group second question: positive integers starting from 1, add one by one, has been added to n, their sum recorded as s, That s = 1 +2 +3 + ... + n (n represents a positive integer), write out the formula to calculate s .This question contains letters and set the question thinking, solving methods reflect the mathematical method is more important The result can be used as a formula, and the application of hierarchical use.In order to help students understand these characteristics, the problem is now read for students to reference.