In the 20 17 Henan civil service examination, the mathematical operation of the line test is a headache for most candidates. It has the characteristics of many test sites, scattered questions and great difficulty, which makes many students lament that they can't prepare for this part of the examination. However, through statistics, we will find that most of the real questions in the national examination can be solved by the most basic problem-solving methods, which means that mastering these methods is equivalent to opening the door to preparing for the exam, and then learning the questions will be handy. Here are some of the most important methods for your reference. For each method, we will sort out its definition core, application environment and specific usage.

(a) divisible

Core: Eliminating Error Options through Separability

Divisibility is different from our thinking of solving problems in the past. It focuses on finding answers rather than calculating results, which can save a lot of examination time for candidates. Because in most cases, the results are integers, so this method has a wide range of applications, and candidates are advised to consider it at the first time.

Application environment: when the stem of the question reflects the divisibility of the answer through words, data or calculation.

Example: In order to concentrate on raising chickens, farmer Zhang San gave his pig to Li Sihe. It is known that there are 260 pigs in Zhang San and Li Si, of which 13% are black-haired pigs and 12.5% are black-haired pigs. How many non-black pigs does Li Si have?

125 b . 130 c . 140d . 150

Answer: c

According to stem information,' Li Siyang pigs 12.5% are black-haired pigs', in which 12.5% can be converted into one eighth, and because the number of pigs is an integer, we can know that Li Siyang pigs can be divided into eight parts, of which 1 part is black-haired pigs, that is, the remaining seven parts are non-black-haired pigs, so we can increase them. Combined with the option, the only thing divisible by 7 is C.

(2) Equation

Core: Formulating equation according to equivalence relation.

Equation method can be said to be a method that most candidates have been exposed to since childhood. It is relatively skilled and easy to master in the three steps of setting, listing and solving. Although the process of solving problems is not as simple and fast as the divisible method, it has a wide range of applications and is one of the commonly used methods in exams.

Application environment: when there are iconic statements, such as "wait a minute", "yes" and "more than ..."

Example: Three vegetable bases, A, B and C, store 5,200 tons of vegetables. If 544 tons are shipped from base A and put into base B, the vegetables in base B are 800 tons more than those in base C, and the weight ratio of vegetables in base A is 7:4, then how many tons of vegetables are there in base A?

From 2256 to 2800.

Answer: d

Scheme 1: After taking out 544 tons of base A, the ratio of Party A to Party B is 7: 4, and the weight of base A corresponds to 7 parts. According to divisibility, radix A can be divisible by 7 at this time, so the original weight of radix A is a number divisible by 7 after subtracting 544. Combined with the options, only D meets the requirements.

Method 2: "The vegetables in base B are 800 tons more than those in base C" in the title. According to this statement, equations can be listed, so consider the equation method. First of all, because there is a proportional relationship between the stems of the questions, we might as well set one copy as X, so that the weights of Party A and Party B are 7x and 4x respectively, and because the sum of the three weights remains unchanged, C is 5200-7x-4x = 5200-11X. Then according to "B-C =800", that is, 4x-(5200-11x) = 800. Finally, x=400 can be found, so the original A =400×7+544=3344 tons. So choose D.

The above is the 20 17 Henan civil service exam preparation shared by Henan Tuhua. I hope it will help everyone. Preparing for the exam is by no means a one-off event. I hope all candidates can wait patiently and get a satisfactory result in the 20 17 Henan Civil Service Examination!