Little knowledge of interesting mathematics in grade three

In a word, interesting mathematical knowledge 1. A short knowledge of mathematics is about 20 to 50 words.

Interesting knowledge of mathematics

Number theory part:

1, there is no maximum prime number. Euclid gave a beautiful and simple proof.

2. Goldbach conjecture: Any even number can be expressed as the sum of two prime numbers. Chen Jingrun's achievement is that any even number can be expressed as the sum of the products of one prime number and no more than two prime numbers.

3. Fermat's last theorem: n power of x+n power of y = n power of z, and n> has no integer solution at 2 places. Euler proofs 3 and 4, 1995 were proved by British mathematician andrew wiles.

Topology part:

1. The relationship among points, faces and edges of a polyhedron: fixed point+number of faces = number of edges +2, which was proposed by Descartes and proved by Euler, also known as euler theorem.

2. euler theorem's inference: There may be only five regular polyhedrons, namely regular tetrahedron, regular octahedron, regular hexahedron, regular icosahedron and regular dodecahedron.

3. Turn the space upside down, the left-handed object can be changed into the right-handed, and through Klein bottle simulation, a good mental gymnastics,

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2. Interesting mathematical knowledge in life

1. A garment worker can produce 4 coats or 7 pairs of trousers per person every day, and one coat and one pair of trousers make a suit. At present, 66 workers produce, how many sets of clothes can you produce at most every day?

Xiao Wang has three stamp albums, one fifth of all stamps are in the first one, n divided by 8(N is a non-zero natural number) is in the second one, and the remaining 39 stamps are in the third one. How many stamps does Xiao Wang have?

Xiao Ming looked at his report card and predicted that if the next math test is 100, the total average score will be 9 1. If he gets 80 points in the next exam, the overall average score will be 86 points. How many times did Xiao Ming take the math statistics exam?

1

To set up X workers to produce coats, you must

4x=7*(66-x)

Then x=42.

So you can produce 4*42= 168 sets of clothes a day.

2

Suppose it has x stamps.

x/5+N/8+39=x

Simplified to 4x/5-N/8=39.

According to the meaning of the question, n is the ending of 8, 4x/5 is an even number, and 39 is an odd number. Then n is the odd tail of 8. Let N=(2t+ 1)*8 get 4x/5-(2t+ 1)=39.

x=( 100+5t)/2

Then 5t is an even number, let t=2w, x=( 100+5*2w)/2=50+5w.

It can be seen that * * * has 50+5w stamps, where w is 0, 1, 2, 3, 4.

At this time N=32w+8.

three

There have been X exams, and now the average score is A.

(xa+ 100)/(x+ 1)= 9 1

(xa+80)/(x+ 1)=86

The two expressions are subtracted, and 20/(x+ 1)=5.

Then x=3 a=88

That is, the results of the existing three exams.

3.20 words of interesting math story

Mathematical Interesting Story 1: Symmetrical Figure of Animal City One day, a butterfly flew around among the flowers in the animal city, and a little dragonfly flew over and said, "Little dragonfly, let's play together.

The little butterfly said, "I am a butterfly and you are a dragonfly." How can we play together? "The little dragonfly said," In the kingdom of graphics, we are a family, and there are many other family members. Don't believe me, I'll show you.

"Along the way, the butterfly saw many beautiful scenery and many animals: beautiful peacocks, cicadas and ladybugs.

Children, are they beautiful? What do you think is beautiful about them? Story 2: the possibility of Zhang San's life and death In ancient times, a confused county magistrate arrested innocent Zhang San because he listened to his master's slanders. During the interrogation, he said to Zhang San, "I will give you one last chance tomorrow, and then I have two signs here, one with the word' death' and the other with the word' life'. What will happen to you children if you let Zhang San smoke? " However, if you want to kill Zhang San, the word "death" is written on both brands. Kid, what will happen if Zhang San smokes again? Fortunately, a friend of Zhang San told him the news.

The next day, the county magistrate asked Zhang San to draw lots at the opening ceremony. Zhang San drew a lot and swallowed it quickly.

The county magistrate had to open another sign and found that the word "death" was written on it. He thought that Zhang San had drawn the word "life" and had to let Zhang San go.

4. Interesting mathematical knowledge, about 300 words, for handwritten newspaper,

It takes 1 hour to burn a rope from one end. Now you need to use this rope and a box of matches to measure the time for half an hour without looking at your watch. You may think it's easy. You just need to make a mark in the middle of the rope, and then measure the time it takes for the rope to burn half. Unfortunately, however, this rope is uneven, thick in some places and thick in others. So this kind of rope burns at different speeds in different places. Maybe it takes only 5 minutes for half of the rope to burn, but it takes 55 minutes for the other half to burn. Faced with this situation, it seems impossible to accurately measure 30 minutes with the rope above, but this is not the case. You can solve the above problem in an innovative way. This method is to ignite at the same time from both ends of the rope. The rope must take 30 minutes to burn out. The two trains run in opposite directions along the same track, and each train runs at 50 miles per hour. When the distance between the two trains is 100 mile, a fly begins to fly from train A to train B at a speed of 60 miles per hour. After it meets the B train, it immediately turns around and flies to the A train, and so on until the two trains collide. We know that the distance between two cars is 100 miles, and the speed of each car is 50 miles per hour. This means that each car has traveled 50 miles, that is, two cars collided one hour later. During the short time from the train to the collision, the fly kept flying at 60 miles per hour, so when the two cars collided, the fly flew 60 miles. Whether the fly flies in a straight line, in a "Z" shape or tumbling in the air. The result is the same. Flipping a coin on the eighth floor is not the fairest way to make a decision. People think that this method is fair to both sides, because they think that the probability of coins upside down and upside down is the same, both of which are 50%. Interestingly, this very popular idea is not correct. First of all, although it is unlikely that a coin will fall and stand on the ground, this possibility exists. Secondly, even if this small possibility is ruled out, the test results show that if you flick the coin in the conventional way, that is, with your thumb, the probability that the coin will still face up when you start throwing is about 5 1%. The reason why this happens is that when you flick it with your thumb, sometimes the coin doesn't turn over, but just rises like a trembling flying saucer. Next time, if you want to choose which side of the coin in the coin thrower's hand is facing up, you should look at which side is facing up first, so that you have a greater chance of guessing correctly. But if that person is holding coins and turning his fists one by one, then you should choose the opposite from the beginning.

5. A little knowledge about mathematics

It is very difficult for pupils with poor grades to learn primary school mathematics. In fact, primary school mathematics belongs to basic knowledge, and it is relatively easy to master as long as you master certain skills. Primary school is a time to develop good habits, so it is very important to cultivate children's habits and learning ability. What are the skills of primary school mathematics?

First, pay attention to the lecture in class and review it in time after class.

The acceptance of new knowledge and the cultivation of mathematical ability are mainly carried out in the classroom, so we must pay special attention to the efficiency of classroom learning and find the correct learning methods. In the classroom, we must follow the teacher's thinking and actively formulate the following steps to think and predict the difference between the problem-solving thinking and the teacher. In particular, we must understand the basic knowledge and basic learning skills, review them in time, and avoid doubts. First, before all kinds of exercises, we must remember the teacher's knowledge points, correctly understand the reasoning process of various formulas, and try our best to remember instead of using "uncertain books to read". Be diligent in thinking, try to think about some problems with your brain, carefully analyze the problems, and try to solve them by yourself.

Second, do more exercises and form a good habit of solving problems.

If you want to learn math well, you need to ask more questions and be familiar with all kinds of problem-solving ideas. First of all, we practice the basic knowledge repeatedly according to the topic of the textbook, and then find some extracurricular activities to help broaden our thinking practice, improve our analytical ability and master the law of solving problems. For some problems that are easy to find, you can prepare a wrong book for collection, write your own ideas for solving problems, and develop a good habit of solving problems in daily life. Learn to keep yourself highly focused.

Third, adjust the mentality and treat the exam correctly.

First of all, the main focus should be on the foundation, basic skills and basic methods, because most exams are based on basic questions, and the more difficult questions are also based on basic questions. Therefore, only by adjusting the learning mentality and trying to solve problems with clear ideas will there be no too difficult problems. Practice more exercises before the exam, broaden your mind, and improve the speed of doing the questions on the premise of ensuring accuracy. Simple basic questions should be grasped with 20 points. Try to do the right thing on rare topics, so that your level can be normal or extraordinary.

It can be seen that the skill of primary school mathematics is to do more exercises and master basic knowledge. The other is mentality, and it is very important to adjust mentality. So you can follow these skills to improve your ability and enter the ocean of mathematics.