What's the difference between horizontal and vertical?

The direction of writing and reading, the complexity of application and calculation are different.

Writing and reading direction: horizontal writing starts from the left end of the horizontal grid of the math book, and the numbers and operation symbols are arranged from left to right in turn, which is more convenient for reading and understanding. Vertical arrangement of numbers and operation symbols from top to bottom requires reading and calculation from left to right.

Application calculation is complicated: horizontal calculation is relatively simple and suitable for simple calculation. Many people like to use horizontal when calculating the result of an expression. Vertical arrangement is more suitable for complex calculation, because it can display all numbers and operation symbols more clearly.