Mathematical reasoning problems must first master the mathematical operation relationship, and analyze and answer the exercises according to the quantitative relationship. Digital reasoning problems can be divided into the following ten types:

1. sum and difference relation. Divided into arithmetic, moving sum or difference.

(1) arithmetic relation. This kind of problem is relatively simple and can be worked out in a short time without practice. It is suggested that when solving this kind of problems, we should use oral calculation.

(2) moving sum or difference. Starting from the third item, each item is the sum or difference of the first two items. It's a bit difficult to do this kind of problem for the first time, but it's easy to do it more.

2. multiplication and division. It is divided into equal proportion, moving quadrature or quotient.

(1) equal ratio. Starting from the second term, the ratio of each term to its previous term is equal to a constant or a arithmetic progression.

(2) Moving quadrature or quotient relation. Starting from the third term, each term is the product or quotient of the first two terms.

3. Square relation

4. Cubic relationship

5. Fractional series. Generally, it is not a big problem to list this number. The key is to regard numerator and denominator as two different series, some of which need simple general division to get the answer.

6. Series with radical sign. This kind of problem is generally not difficult, as long as it is simple to master the root number. Limited to poor computer skills, I can't type the root number and list questions.

7. Prime sequence

8. Double series.

(1) every two projects are grouped, for example

1, 3, 3, 9, 5, 15, 7, (2 1) the first and second items, the third and fourth items, and so on. The ratio of the last item to the previous item is 3 2, 5, 7,/kloc-0.

1/7, 14, 1/2 1, 42, 1/36, 72, 1/52, () are a group, and the last item in each group is equal to the previous one.

(2) The two series are separated, and one of them may be irregular, but as long as we grasp the series that changes regularly, we can get the result.

22, 39, 25, 38, 3 1, 37, 40, 36, (52) consists of two series, 22, 25, 3 1, 40, () and 39, 38, 37, 36, which are separated from each other.

34, 36, 35, 35, (36), 34, 37 and (33) are separated by two series, one increasing and the other decreasing.

(3) The number in a series has decimals, in which the integer part is a series and the decimal part is another series.

9. Combination series.

This series is the most difficult. There is almost no problem with the first eight series, but the combination of eight series relationships in pairs or even the abnormal combination of three relationships has formed a more difficult problem. The most common are the combination of sum-difference relationship and multiplication-division relationship, and the combination of sum-difference relationship and cube relationship. Only when we are familiar with the above eight relationships can we solve this kind of problem better and faster.

10. Other series.

()A 40 B 32 C 30 D 28

Choose C.2 = 1 * 2,6 = 2 * 3,12 = 3 * 4,20 = 4 * 5, and the next one is 5 * 6 = 30 1,1,2,6,24.

Select C. The last item = the previous item * increasing sequence. 1= 1* 1, 2 =1* 2,6 = 2 * 3,24 = 6 * 4, and the next one is 120=24*5 1.

Choose B, every three items are a repetition, and then subtract them to get 3, 4 and 5. The next repetition is also 3, 4, 5, and the inference is 25. 27， 16，5，()， 1/7 A 16 B 1 C 0 D 2

Choose B, which is the cubic of 3, the quadratic of 4, the 1 power of 5, the 0/power of 6 and the-1 power of 7.

Some of these series also belong to combinatorial series, but they are classified as other series because of their different relationships with sum, difference, multiplication, division and square. This series also has many general problems.

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