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以“破译密码”为素材的试题取材于现代生活,不仅反映了有价值的基础数学知识、基本数学思想的广泛应用,还考查了学生灵活应用、自主探索的能力,充分体现了新课程标准的教育理念.下面采撷两道典型例题并予以解析,旨在探索题型规律,揭示解题方法.例1(湖北武汉市高考模拟题)现代社会对破译密码的难度要求越来越高.有一种密码把英文的明文(真实文)按字母分解,其中英文的a、b、c、…、z的26个字母(不论大小写)依次对应1、2、3、…、26这26个自然数,见表格:
The test questions based on “breaking passwords” are based on modern life. They not only reflect the extensive application of valuable basic mathematics knowledge and basic mathematics ideas, but also examine the students’ abilities of flexible application and independent exploration and fully embody the new curriculum. The standard education concept. The following pick two typical examples and analyze it, aiming to explore the laws of the type of questions, reveal the method of solving problems. Example 1 (simulation test of Wuhan entrance exam in Hubei) Modern society is increasingly demanding the difficulty of deciphering the password. There is a password that divides the English plain text (authentic text) into letters, in which the 26 letters of English, a, b, c, ..., z (in either case) correspond to 1, 26, 26, 26, 26 Natural numbers, see table: