A few math questions. Right10

1.The decimal system is relative to the binary counting system, and it is the most commonly used counting method in our daily life; The counting method in which the rate of advance between every two adjacent counting units is ten" is called "decimal notation".

Comparison of the size of integers: first look at the number of digits, the number with more digits is larger; The number of digits is the same, and from the highest digit, the number on the same digit is larger.

2) Comparison of the size of the decimal number first compare the integer part of the two numbers, and the number with the larger integer part is larger; The integer part is the same, and then look at their decimal part, from the high position, according to the number comparison, the number on the same digit is larger.

3) Comparison of the size of the fraction: the fraction with the same denominator is larger; fractions with the same numerator, fractions with smaller denominator are larger; Scores with different denominators, the first score is compared.

3.The numerator and denominator of the fraction expand (or shrink) by the same multiple at the same time, adding 0 to the end of the decimal or removing 0 to keep it the same size. Adding or removing 0 at the end of the decimal is equivalent to expanding (or shrinking) the denominator of the fraction by a factor of 10

4.Look at what is behind your decimal point.

For example, if you move another bit, it will increase by 10 times.

Moving left is reduced by a factor of 10.

5.Prime numbers, composite numbers.

Prime numbers are also called prime numbers. The number of prime numbers is infinite. Composite Number:

In addition to 1 and itself, the divisor of a number has other divisors, and this number is called a composite number. 2 is not a composite number, and 1 is neither prime nor composite. The prime factor is the divisor:

Factors of a composite number, and these factors are all prime numbers

Multiples, factors.

In division, if the dividend is divided by the divisor, and the quotient obtained is a natural number with no remainder, then the dividend is said to be a multiple of the divisor, and the divisor is the factor of the dividend.

3.Shift to the right and become larger, move to the left and become smaller;

For ease of expression, note that this cube is ABCD-A'b'c'd', 8 vertices, 12 edges;

According to the title, if any of the three adjacent edges of each vertex is taken once, the number of the vertices is added by 1;

It can be obtained: After the operation is completed, the number on each vertex increases the number of times that the three adjacent edges are taken compared to the original;

Divide the 8 vertices into two groups: (a, c, b.)'、d') and (b, d, a'、c'), then each group of 4 vertices has a total of 12 adjacent edges, and the 12 edges of the cube are exactly not repeated;

At the beginning, the sum of the numbers on the two groups of vertices is , respectively, you may wish to set 12 edges to be taken a total of n times, then after the operation is completed, the sum of the numbers on the two groups of vertices is exactly increased by n compared with the original, becoming n, n+1;

Assuming that after the operation is completed, the numbers at the 8 vertices are divisible by 3, we get: n, n+1 are divisible by 3, but n, n+1 are two consecutive integers, and it is impossible for them to be divisible by 3, and there is a contradiction, so it is impossible to make the numbers at the 8 vertices divisible by 3 by such an operation.

No, each point is only on the same edge as the other 3 points

If the numbers cannot be repeated, there is no solution.

If you consider the order of operations, there is no solution.

Without considering the order of operations, all possible solutions are as follows:

The first line? +？9=4, then? +？=13=10+3=9+4=8+5=7+6

Notice the first column? +？=4,If it's less than ten,Only 2+2=3+1=4+0=4。。。

So the question is, can fill-in-the-blank be reused? Then, is it 1 10 or 0 9???

If the first column is in the correct order of operation, there is no correct result; But regardless of the order of operations, there is an answer upstairs.

Finally there is an interesting question, waiting.

1.Each interior angle of a polygon is 150°, then the polygon is 12 sides, and from one of the vertices of this polygon there are n(n-3) 2 diagonals.

2.Each inner angle of a polygon is 20° more than 3 times the outer angle of the adjacent polygon, then the sum of the inner angles of the polygon is 1260 degrees.

3.Xiao Ming bought a total of 16 stamps of 80 cents and 2 yuan at the post office, spent 18 yuan and 8 jiao, if the stamps of 80 cents were bought x and 2 yuan were bought y, then the title can be listed as a binary equation system of x + y = 16 and.

4.The positive integer solutions of the inequality group 5x-2>3 (x+1), x-2 14-3x are 3 and 4.

5.The purchase price of a store is 1000 yuan, the selling price is 1500 yuan, due to the poor sales situation, the store decided to reduce the price**, but to ensure that the profit is not less than 5. Then, this item can be discounted at a minimum of 7%**.

6.In the formula ax+by, when x=3, y=-2, its value is 8; When x=2, y=5 and its value is -1, then the formula should be 2x-y

7.If 2(x-2) -18=0, then the value of x is 5 or -1

8.The following statement is false: (d) The ordinate of all points on the axis is equal to 0cPoint (-1,1) and point (1,-1) are not the same point d

The points (-2,3) and points (3,-2) are symmetrical with respect to the origin.

9.Add 2 to the abscissa of each apex of abc to get a b c The ordinate is unchanged, connect the three vertices a, b, and c, and the resulting a b c is the original abc(b) (a) to the left to translate 2 units to get (b) to the right to translate 2 units to get (c) to translate 2 units up to get (d) down to translate 2 units to get (d) down to get 2 units.

10.If there is no solution for the inequality group a-x>0 and x+1>0, then the value range of a is (b).

450÷44=10……10

Strategies in the Teaching of Problem-Solving in Primary Mathematics.

1) Combination of classroom knowledge and practical activities.

At present, the teaching is mainly based on the knowledge in the textbook, and there are few or basically no practical activities corresponding to the textbook, so that students cannot apply the knowledge they have learned to practical life, and the problem solving only relies on the knowledge in the textbook, but that is far from enough, and over time, the ability of students to use mathematical knowledge to solve problems declines or even does not. Therefore, teaching should pay attention to the arrangement of students' practical activities, and effectively apply the knowledge learned in textbooks to life.

2) The importance of communication between teachers and students.

At present, the teaching is still in the stage where the teacher talks and the students listen, and the interaction between the teacher and the students is very little, and the boredom of the classroom directly leads to the efficiency of the students' listening to the class, as well as the thinking problems after class, so that the way of thinking about the problems of students is fixed step by step, and the improvement of learning efficiency is not used. Teachers should encourage students to speak more and think about problems from multiple perspectives in the teaching process, so as to inspire and promote the development of students' thinking in this classroom mode. Mathematics problem-solving teaching is an important channel to improve students' ability to solve practical problems, so by improving the teaching mode, improving students' problem-solving ability, comprehensively enhancing students' interest in learning, and cultivating students' learning efficiency.

3) The necessity of setting specific problem scenarios.

4) Teachers should also pay attention to the discussion among students in the problem-solving teaching mode.

In the process of problem solving, students are divided into groups to communicate, which is conducive to developing the way students think about problems, forming an innovative mode of problem solving, and improving students' ability to solve problems in life while cultivating problem-solving strategies. Students solve problems well in communication, which can cultivate students' joy of learning. In short, in the teaching process, teachers should advocate a variety of methods to solve problems, and also put forward more innovative questions, so that students can think about problems from different angles, so that students can go through a thinking process from finding problems to raising problems and then solving problems.

5) Cultivate problem-solving skills while getting high scores.

In the process of primary school mathematics teaching, students need to grasp the focus of the test questions and be proficient in the relevant formulas, although this teaching mode can effectively improve students' performance to a certain extent, but it does not play a significant role in students' problem-solving ability. As a primary school mathematics teacher, its main job should not be to train students into a group of machines that can only score high, and ignore the cultivation of students' problem-solving ability, and at the same time arouse students' interest in learning mathematics, so that Chinese primary school students are not afraid of mathematics, but bravely face and solve it.