Step 1: There are five different ways to get a math book from the top shelf.

Step 2: There are three different ways to get a Chinese book from the middle shelf.

Step 3: There are two different ways to get English books from the lower shelf. According to the principle of step-by-step multiplication and counting, there are N=5×3×2=30 in different ways.

So take three books from the bookshelf, a math book, a Chinese book and an English book. There are 30 different ways to take it.

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.