There are two kinds of math exercise books, one is big, the other is small, and the small one is generally horizontal. The middle line divides the whole exercise book into two large exercise books, which are also horizontal. The first one has no vertical line in the middle.
The second format is the same as the small exercise book, but it is a little bigger. The third format is half horizontal and half empty. There are generally small exercise books below grade three, and large exercise books of the first kind above grade three.
Introduction to primitive mathematics
Bourbaki is a collection pen name. In the late 1920s, there were several college students in Paris University, France, determined to rearrange all the mathematics so far with the latest ideas. These fledgling young people intend to write a math book and establish their own system in three years.
Of course, this is an excessive expectation. As a result, they have been writing for 40 years and haven't finished it yet, but in the process, the Bourbaki school was formed. They are unique in mathematics, and regard all mathematics as a system deduced according to different structures.
Therefore, it is famous for structuralism in the world and won the praise of mathematics. The Bourbaki School even influenced middle school textbooks, and it is reflected in the middle school textbooks translated by China in recent years.