1. First, read the topic carefully and find the target number and the number in the grid. The target number is the sum or difference of the numbers to be circled, and the numbers in the grid are optional numbers.

2. Secondly, look for two or more adjacent numbers in the grid to make their sum or difference equal to the target number. Adjacent numbers can be horizontal, vertical or diagonal. You can draw different circles with different colors to distinguish different combinations.

Finally, check the answers to see if there are any omissions or mistakes. If so, you can modify or supplement your circle. If not, it's over.