The function of small plaid book in mathematics is that it is free to write, no matter how small it is, it can quickly find a suitable reference and will not be crooked. 2. Checked books can be written horizontally and vertically, which has no influence at all, because it doesn't have a fixed writing direction like horizontal lines. 3. It is also very convenient to draw pictures on the grid book, not only icons, but also interesting small pictures, no problem, so the grid book is also adopted by many handwritten books. This is similar to the grid book, but the grid book is not suitable for drawing icons, and it will be easy to spend your eyes. 4. The grid book is also very suitable for drawing mind maps, flowcharts, block diagrams and text boxes.