Regardless of the differences between books, we can choose five of the nine books, and there are 95 ways to choose.

There is no math book, that is, there is a C65 way to take any five of the other six books.

Indirect method, * * has C95-C65= 120 methods.

Basic counting principle and application of two commonly used extended data arrangements

1, addition principle sum classification counting method;

Each method in each class can accomplish this task independently; The specific methods in the two different methods are different from each other (that is, the classification is not heavy); Any method to accomplish this task belongs to a certain category (that is, classification does not leak).

2. Multiplication principle and step counting method:

One method of any step can't complete this task, and only by continuously completing these n steps can this task be completed; Each step is independent of each other; As long as the methods used in a step are different, the corresponding methods to complete it are also different.