1. Addition and subtraction of fractions: In addition and subtraction of fractions, there are some common mistakes, such as different denominators, general errors and reduction errors.
2. Multiplication and division of decimals: In the multiplication and division of decimals, the error-prone places include the position of decimal point and the operation rules of multiplication and division.
3. Properties of triangles and quadrangles: Among the properties of triangles and quadrangles, mistakes are easy to make, including the sum of the internal angles of triangles is 180 degrees, and the diagonal of parallelograms is equally divided.
4. Calculation of area and volume: In the calculation of area and volume, errors are easy to occur, including unit conversion errors and calculation formula errors.
5. Calculation of percentage: In the calculation of percentage, mistakes are easily made, including the conversion between percentage and decimal, the operation rules of percentage, etc.
6. Solving the equation: When solving the equation, there are moving items, merging similar items, substituting unknown values, etc.
7. Similarity of geometric figures: In the similarity of geometric figures, the places that are easy to make mistakes include the calculation of similarity ratio and the judgment of similar figures.
8. Collection and collation of data: In the collection and collation of data, error-prone places include wrong records and wrong classification of data.