“分类”是常用的解题策略之一。在解答某些较复杂的小学数学竞赛题时,有的可根据题意,按照一定的规则,把有关的条件分成若干类,照此分类进行解答,这样不但条理清楚,而且不易出错。下面举例说明之。例1 计算:1/2+1/3+2/3+1/4+2/4+3/4+……+1/(80)+2/(80)+…+(79)/(80) “Classification” is one of the commonly used strategies for solving problems. When answering some more complicated primary school mathematics competition questions, some may, according to some questions and according to certain rules, classify the relevant conditions into several categories and solve them according to the classification so that they are not only well-defined but also not prone to error. Here's an example. Example 1 Calculated: 1/2 + 1/3 + 2/3 + 1/4 + 2/4 + 3/4 + ... + 1 / (80) + 2 / (80) + ... + 80)