Gu Xu was still very patient: "Little brother, let's continue watching. On the first day, we climbed up and fell down again...
When the snail climbed to the 4th day, it climbed up on the 5th day..."
Gu Xu said as he took the eraser and climbed up to behind the line he drew. Once the snail has climbed to the ground, it does not need to come down. How much did it climb on the fifth day?
"Nine decimeters." The little boy followed Gu Xu's train of thought and analyzed.
"That's right!" Gu Xu nodded, "Including the 2 decimeters it climbed on the first, second, third, and fourth days, how many decimeters is the total?"
The little boy counted with his little hands: "2 plus 2 plus 2 plus 2, equals 8."
"In addition to the fifth day..." Gu Xu continued to guide.
"8 plus 9 is equal to 17 decimeters." The little boy suddenly realized, he sighed, "I know!"
He was excited: "Thank you, brother!"
Seeing that his son knew how to do it, his father was also very happy: "Oh, you have solved a big problem for me."
"You're welcome, uncle, just pay, one dollar."
"It's only one yuan, so cheap!"
Gu Xu hesitated: "Uncle, we make small profits but quick turnover."
"Son, don't you still know a lot of questions that you don't know? Hurry up, let your brother teach you." The father wished that Gu Xu could teach his son all the questions he didn't know.
"Brother, there is this way, this way, here!"
Gu Xu couldn't laugh or cry immediately, "Oh my God, how many things do you know!"
He kept smiling: "It doesn't matter, I will teach you every step!"
After a while, he taught the little boy more than twenty questions, both large and small.
"Is there more?" Gu Xu asked again.
The little boy flipped through his homework and read it several times: "No more!"
He had a smile on his face: "Thank you, brother!"
It's good now, he doesn't have to be scolded by his father anymore!
The father was very happy: "Very good, very good!"
He sighed: "I finally don't have to worry about my son's homework. Every time I teach my son homework, I feel like I'm staring at him for a long time without being able to come out."
Gu Xu said with a smile: "Uncle, I just talked about five big questions, ten intermediate questions, and eight small questions, a total of 63 yuan."
The father took out 100 yuan and said, "No need to look for it. I'm troubling you today."
"Thank you, uncle!" Gu Xu said.
The father said and left happily with the little boy.
Lan Ruosi was very surprised: "He actually left without change?"
Gu Xu calmly said: "Didn't you see that he was upset before he came? We have solved a big problem for him. It would be better to give him more if he is happy."
Lan Ruosi pursed her lips, and she understood immediately.
Gu Xu smiled: "This is not difficult, isn't it?"
Lan Ruosi nodded.
"How about you be the next one?" Gu Xu tempted.
"Ah!" Lan Ruosi was shocked and shook her head.
She looked very simple, but she was still a little scared.
After a while, a middle-aged woman in her 40s came with two children. The older one was a boy who looked about thirteen or fourteen years old, and the younger one was a girl who looked about eight or nine years old.
Before Gu Xu could say anything, the middle-aged woman said, "I heard that there is a young man here who specializes in tutoring homework, right?"
Gu Xu said politely: "Yes, what can I do, aunt?"
"Quick, quick, help them with their homework! I'm almost worried to death." The middle-aged woman said and asked the children to take out their homework books.
Gu Xu looked at Lan Ruosi: "Little porridge, look, there are two here. Otherwise, you can help tutor one of them?"
Lan Ruosi hesitated and said nothing.
Gu Xu added: "Look, it's not good to make people wait."
"Okay!" Lan Ruosi looked at the little girl, "Then let me tutor this little girl!"
Lan Ruosi felt that little girls should be more well-behaved and easier to teach.
Lan Ruosi said softly: "Little sister, what can't you do?"
The little girl pointed to the question in the homework book: How can four triangles be built with six matches?
Gu Xu saw that Lan Ruosi was willing to take action, and he looked at the boy: "Little brother, what's wrong with you?"
The little boy also took out his homework book and pointed to the questions on it.
"Auntie, it's ready!" Lan Ruosi took the six matches the little girl brought and finished setting them in a few seconds.
Gu Xu was unexpectedly surprised. Lan Ruosi solved it without even seeing the question.
I go!
What's going on in his little wife's head?
The middle-aged woman was shocked: "Little girl, you are really amazing. I used toothpicks to solve this problem at home, but I couldn't solve it for several days.
My child has been arguing with me for a long time. He will have a tutoring class tomorrow. If he can't answer the question, he will be laughed at by his classmates.
I am so worried that I don’t know what to do!
You actually did it in a matter of seconds.
This really solved a big problem for me. "
Lan Ruosi smiled: "Auntie, actually, everyone has a fixed mindset on this question. Most people think about a flat surface. You can just stand it up."
Gu Xu felt proud of her: My little daughter-in-law is really amazing.
Later, I married her and had children.
When a child comes to ask me what to do, I tell him three words directly: ask your mother!
Well!
It doesn’t seem right to look for your mother!
It should be, ask your mother to teach you!
Gu Xu was shocked: Did I think too far?
In fact, it’s not that far away, maybe we’ll be there in the blink of an eye.
"Brother, how do you solve this problem?" The little boy watched his sister solve it and felt very anxious.
Gu Xu read out the question: "The cube of the single digit and tens digit of grandpa's age this year is a four-digit number, and the fourth power is a six-digit number. These two numbers just make up the numbers 0, 1, 2, and 3. , 4, 5, 6, 7, 8, and 9 are all used. How old is grandpa?
As soon as Gu Xu finished reading, the answer came casually: "81 years old!"
There were varying degrees of surprise on the faces of everyone present.
Lan Ruosi was even more amazed: Gu Xu's calculation ability is so strong.
The little boy blurted out: "Brother, you are so awesome. You knew the answer just after reading the question."
"Because, when I read the questions, my brain started calculating!"
The little boy looked confused, as if he was listening to a book from heaven.
Gu Xu smiled: "Actually, this question is very simple. The key point is that you must first be familiar with cubic numbers in your mind.
The reversed number cube is a four-digit number, 10 cubed is 1000, 21 cubed is 9261, and 22 cubed is 10648, which is a five-digit number.
The number after the swap is between 10 and 21, so we narrowed the range.
Continuing to look at the following conditions, the fourth power is a six-digit number. We can start with a slightly larger number.
The fourth power of 17 is 83521, the fourth power of 18 is 104976 six-digit number, the fourth power of 19 is 130321, the fourth power of 20 is 160000, the fourth power of 21 is 194481, and the fourth power of 22 is 5153632 , which is seven digits.
The range narrows again, between 18 and 21.
Then, we are left with the last condition, which is used from 0 to 9.
After the grandfather's age is reversed, it will be between the numbers 18 and 21.
First remove the most repeated 20, then remove 19 and 21, the fourth power has repeated numbers.
Then the answer is 18. If you flip it around, it’s 81. "
Gu Xu finished speaking in one breath.
He looked at Lan Ruosi: This is thanks to his little wife who made things difficult for him just now.
I didn't expect it to be such a coincidence.
