1, number and algebra: this is the most common in mathematics. Decimals, decimals can be converted into fractions, fractions and decimals can be converted into each other, and fractions and decimals can also be converted into percentages.
2. Geometry and graphics: a rectangle with two opposite sides with different lengths, named length and width respectively.
3. Statistics and probability: sector statistics is a special form of broken-line statistical chart, which represents data with smaller equal area.