The legal provisions are as follows:

0+ 1= 1?

1+ 1=2?

1+2=3?

2+3=5?

3+5=8?

5+8= 13?

Extended data:

Addition and subtraction between numbers is a common, simple and very basic law. The general feature of this law is that the difference between numbers is relatively small and will not increase or decrease by multiples. Usually, we should practice more, sum up the characteristics of identifying questions, and use various methods flexibly to solve problems.

Find a way to fill in numbers regularly:

1. Judge whether there are laws such as arithmetic, higher-order arithmetic and equal proportion.

2. Do difference, sum and compare.

3. Deduce the number to be filled in according to the law.