有的习题用“估算———确认———破解”的思路来分析思考,能迅速找到答案。例四个连续的自然数的倒数之和等于1920,则这四个自然数两两乘积的和等于多少?一、估算根据条件,经初步计算,确定四个连续自然数的范围。由于四个连续的自然数的倒数之和等于1920,而1920介于1620与202 Some exercises with “estimation --- confirm --- crack” train of thought to analyze thinking, can quickly find the answer. Example four consecutive natural numbers equal to the sum of 1920 equal to 1920, then the four natural number two and two equal to the sum of the product? A, according to the conditions of the preliminary calculation, to determine the scope of four consecutive natural numbers. Since the sum of the reciprocals of four consecutive natural numbers is equal to 1920, 1920 is between 1620 and 202