I tried two methods:
First, I used the pen step by step, until later, I fainted and didn't know where I was, and then I had to give up;
Secondly, I took out my calculator. I calculated it patiently twice, but I found that the results of the two times were different, which showed that I was still wrong.
I have tried both methods for more than an hour, and there is no result yet. It's really annoying. I sat down and took several deep breaths. At this moment, it suddenly occurred to me that the teacher said such a question in class:
1+2+3+4+5+6+7+8+9=?
The teacher guided us to discover the law step by step in the conversation. Since1+9 =10,2+8 =10,3+7 =10,4+6 =10, the title can be written as follows:
1+2+3+4+5+6+7+8+9
=( 1+9)+(2+8)+(3+7)+(4+6)+5
= 10+ 10+ 10+ 10+5
=45
In this way, it is convenient for us to do the problem, and the head and tail are paired to make up 10. Is that included in this formula? I picked up a pen and paper and worked out: 1+99 = 100, 2+98 = 100, 3+97 = 100. ...
Then I was puzzled again, because 1~99 * * * is 99 numbers, so there must be a number that doesn't match it. Which number doesn't match? I continue to observe the addition formula of 1~9 above. The numbers at the end of 1~4 are all paired with it, and the number 5 in the middle is not paired with it. Are there any numbers in 1~99 that can be matched with it? I thought about it: 50 is the middle number, and the numbers on both sides of 50 are 49 and 5 1, 49+5 1 = 100, so the numbers of 50 are not comparable. Therefore:
1+2+3+4+……+96+97+98+99
=( 1+99)+(2+98)+(3+97)+……+(49+5 1)+50
= 100+ 100+ 100+……+ 100+45
=4900+45
=4950
This difficult problem was finally completed with my determination not to give up. This incident made me understand that there is no such thing as a free lunch. Only by making up your mind can you overcome the problem, and only by facing the problem directly can you succeed!