Briefly introduce you to several ways to do the problem:

Mathematical operation, as one of the most difficult and time-consuming questions in the national civil service examination, is the most easily given up by many candidates, but at the same time mathematics is the most skilled. In other words, the most likely topic of the exam is mathematical operation. In fact, most of the questions in the quantitative relationship part of the exam require each candidate to solve them quickly within one minute. It is really impossible without skills. Therefore, through long-term research, Chinese public education experts have summarized the answering skills of the quantitative relationship part as follows:

First, grasp the problem as a whole and grasp the questioner's thinking.

Example 1 Open three water pipes A, B and C to drain water into the pool, 12 minutes to fill the pool; Open three water pipes (B, C and D) to drain water into the pool, and the pool can be filled in 15 minutes; Open water pipes A and D to drain water into the pool, which can be filled in 20 minutes. If the four water pipes A, B, C and D are opened to discharge water into the pool, the pool needs (

) It can be filled in minutes.

A.25

20 C. 15 D. 10

Chinese public analysis: choose D. The questioner of this question tests the overall grasp ability of the candidates. Open three water pipes A, B and C to drain water into the pool, and the pool can be filled in 12 minutes. Now add D pipe to help the three water pipes A, B and C, so the time is definitely less than 12 minutes, so choose D in this question.

Second, the stem information is directly proportional to or multiple to the options: think multiple, want to divide equally.

Example 2 The passenger train is 250 meters long and the freight train is 350 meters long. They are driving in opposite directions on parallel tracks. It takes 15 seconds from the meeting of two heads to the separation of two tails. It is known that the speed ratio of passenger trains to freight trains is 5: 3. What is the speed difference between the two cars?

A. 10 m/s

B.15m/sec c. 25/ sec d. 30/ sec

Chinese public analysis: choose a, this question asks about the speed difference between the two cars. So when doing the problem, look for data directly related to the problem. The speed ratio of bus and truck is 5: 3, while the speed ratio of B and C is exactly 5: 3. It is inferred that the speed difference between the two cars is10 m/s.

The ratio of football to basketball in school is 8: 7. Buy some football first, then the number ratio between football and basketball becomes 3: 2, and then buy some basketball, then the number ratio between football and basketball becomes 7: 6. As we all know, we bought three more football than basketball. How many footballs are there?

A.48

B.42 C.36 D.30

Chinese public analysis: Choose A, the ratio of football to basketball is 8: 7, and options A and B are exactly 8: 7. Inferring that they are the number of football and basketball respectively, only 48 is a multiple of 8. So choose a.

Third, there is really no time to give up and choose different options according to parity.

Example 4 The labor department in a certain place rented two classrooms, A and B, to carry out practical talents training in rural areas. Both classrooms have five rows of seats, a classroom 10, and b classroom with 9 people. Two classrooms held this training for 27 times in the month, and each training was packed, with 1290 person-times in the month.

How many times has classroom A held such training this month?

A.8

10

Chinese public analysis: choose D. If you really don't have time to complete the mathematical operation, you can choose something different according to the parity. Only D is an odd number in this problem, so we can boldly infer that D is chosen, and the correct rate of this method can reach over 60%. Of course, this problem can be solved by avoiding the same cage, equation, profit and loss thought and so on. And the answer is really D.

Fourthly, there is an additive relationship between the stem information and the options.

Example 5

20 people 15 days can do a job. Now working for three days, five people are transferred to plant trees, and the rest continue to finish the rest of the work. How many days will it take to finish the work?

A. 16

17

I noticed that after working in the topic for 3 days, when we worked out the remaining working days, many candidates would choose the wrong option under the condition of high intensity and high tension in the exam, so the questioner set a trap for us. Note that 16+3= 19 in the option, so it is bold to infer that 19 is the correct option.

5. Cleverly solve the clock problem

It's 4 o'clock now. 13.

What is the angle between the hour hand and the minute hand?

0.30 degrees

45 degrees C.90 degrees d 120 degrees

Chinese public analysis: choose C. If the time denominator of the stem or option is 1 1, remind the candidates to think about the angle difference between the hour hand and the minute; The denominator of time appears 13, reminding the angle of hour hand and minute to sum. If the most direct way to solve this problem is to dial or draw directly with a watch, it is not difficult to find that the angle is 45 degrees after observation. Of course, if the angle difference of some questions is not very big, it is recommended that the majority of candidates bring a watch and protractor, which can be solved.

6. Choose the one with the highest frequency.

Example 8 After converting a simplest true fraction m/7 into a decimal, if the sum of several digits after the first decimal point is equal to 20 1 1, find the value of m. ..

A.2 or 6

B.3 or 5 C. 1 or 4 D.4 or 6.

Chinese public analysis: choose D, 4 and 6 appear twice in this question, and boldly infer that 4 and 6 are correct options, because if 3 or 5 in this question is the correct first item, you only need to calculate one of 3 or 5 to choose. In order to increase the difficulty of calculation, the author gives relevant interference options. To calculate this problem, we must first calculate that m/7 is a cycle of 0. 142857, the sum of a cycle segment is 27,201/divided by 27 quotient 73, and the remainder is 13, indicating that the sum of the remaining two or three digits is/after 73 cycles.

Seven, according to common sense, substitution and exclusion

According to legend, there was a miser in ancient times who left 13 gems before he died. Instruct three daughters: the eldest daughter can get 1/2, the second daughter can get 1/3, and the third daughter can get 1/4. After the old man died, it was difficult for the three daughters to be distributed according to the will anyway, so they had to discuss it with their uncle. When my uncle learned the story, he said, "Your father's will can't be broken, but you can't bury it with such a precious thing. I'll think of something about it! " Sure enough, my uncle quickly divided the jewels, and all three sisters took their fair share of the jewels. Do you know how my uncle distributed it?

A.6、3、4

B.7、2、4

C.6、5、4

D.6、4、3。

Chinese public analysis: choose d, the biggest difficulty of this question lies in the length of the question, and the candidates can read it in one minute.

They are almost the same, so we suggest that candidates read the relevant contents of the data part directly related to the problem when reading mathematical operations. This problem is because the eldest daughter can get 1/2, the second daughter can get 1/3, and the third daughter can get 1/4. The sum of C items is not equal to 13 because the three daughters are ranked more than one. So choose D.

Eight, digital sensitive solution of indefinite equations

Example: Students in group 10 A gave 28 walnuts, students in group B gave 30 walnuts, students in group C gave 3/kloc-0 walnuts, and students in three groups * * * gave 365 walnuts. Q: How many students are there in the three groups?

A、

1 1 B、 12 C、 13 D、 14

Chinese public analysis: choose B. If this question lists the indefinite equation according to the meaning of the question, 28X+30Y+3 1Z=365, and then the answer is B. But if the majority of candidates are sensitive to numbers, this question can be changed to: 28 days in a normal month, 30 days in a small month, and 3/kloc-in a big month. How many months are there in a year? If the questioner asks this question, then everyone believes that they can work out the answer quickly.

Nine, the use of extreme value

Example: 1 1 When a ship goes downstream with t 1 and goes upstream with t2, what will happen to t 1+t2 when the current speed increases?

largen

B, smaller C, constant D, unable to judge.

Chinese public analysis: choose A. Remind the majority of candidates that in the online test, more than 90% of the questions will not choose options similar to C and D. We can solve this problem with special values, and the best special value is the limit. Suppose the current speed of a certain day is infinite, so that the ship can never go back. There was a limited time before, and then there was an infinite time, so the time became longer.

Ten, the number of last resort, to recognize the difficulty.

Example 12 conducted a survey on 0/00 employees of a certain unit, and found that they like watching football matches, movies and plays. Among them, 58 people like watching football matches, 38 people like watching dramas, 52 people like watching movies, 18 people like watching football matches and dramas, 16 people like watching movies and dramas, 12 people like watching all three, and only one likes watching movies.

One, 22 people

B, 28 people C, 30 people D, 36 people

In terms of difficulty, the questioner simply doesn't want the candidates to answer. This time depends on whether we dare to choose. In the words of Chinese public education experts, the questioner closed a door for the majority of candidates (the topic is difficult), but at the same time opened a window, because according to normal thinking, when we can't do it, we will use substitution method, and A is the first substitution, which can save some time for our candidates. Through summary, it is not difficult to find the quantitative part of the test questions: the most difficult answer is often in A, and the easiest answer is often in D; The difficult but reversible answer is B, and the easy but time-consuming answer is C. However, the correct rate is generally around 60%.

The above is a summary of the skills related to the mathematical operation of the line test by Chinese public education experts. The above examples are all from the national examination questions. I hope to bring help to the majority of candidates.

If in doubt, please consult the public education enterprises in China.