Question: 1, 2, 3, 5, 8, (), (), (), find the numbers in brackets according to the law.

Answer process:

5+8= 13。

8+ 13=2 1。

13+2 1=34。

Starting from the third number, each number is equal to the sum of its first two neighboring numbers. So put 13, 2 1 and 34 in brackets.

It's easy to find a method in primary school. Only add, subtract, multiply and divide, there won't be too much trouble to solve the square, although sometimes there is a square in addition, subtraction, multiply and divide, and there is generally no general formula.

Skills to find standard questions;

1, observe first, what are the characteristics, and then check several commonly used methods in turn, such as difference, what is the operational relationship between adjacent three items, if the numbers change dramatically, you can consider squares and cubes, and be familiar with the values of some commonly used squares and cubes.

2. Common factor method: multiply each number by the least common factor, and then find the law to see if it is related to n, or 2n, 3n.

3. When solving the general term series, we can guess the general term formula of this series quickly and accurately through the first few terms, and then prove it by mathematical induction or reduction to absurdity or other methods.