数学兴趣小组活动时,老师出了这样一道题:将自然数按下面的规律分组:(1、2),(3、4、5、6),(7、8、9、10、11、12),(13、14、15、16、17、18、19、20),……第2003组的第一个数是多少?最后一个数是多少?题目一出示,同学们就议论开了,不一会儿,兰兰就举手发言了。兰兰说:要解答这道题,首先要仔细观察这一组自然数,找出它们的分组规律, Mathematic interest group activities, the teacher came up with a question: the natural number according to the following rules: (1,2), (3,4,5,6), (7,8,9,10,11,12) , (13,14,15,16,17,18,19,20), ... What is the first number in Group 2003? What is the last number? When the first item is presented, the students open the discussion and do not A moment later, Lan Lan raised his hand. Lan Lan said: To answer this question, we must first carefully observe this group of natural numbers to find out their rules of grouping,