The format of expression refers to the expressions listed in the calculation of numbers (or algebraic expressions), including numbers (or letters instead of numbers) and operation symbols (four operations, powers, roots, factorials, permutations and combinations, etc. ).

According to the different calculation methods, the formulas are generally divided into horizontal and vertical. Unlike expressions, expressions are expressions that connect data of the same type (such as constants, variables, functions, etc.). ) Use operation symbols according to certain rules, and expressions are expressions that connect numbers through operation symbols to calculate results, and need an equal sign.

The format of exercise books is strictly in accordance with the following requirements:

1, the horizontal formula is written from the left end of the horizontal grid line in the math book.

2. Vertical style: the first addend of horizontal style is written below the second addend, and the plus sign of horizontal style is aligned with the plus sign. The same numbers of addend, addend and sum must be aligned.

3. After calculating the vertical columns, don't miss the horizontal numbers.