1, the meaning of score: divide a whole into several parts on average, and the number representing 1 or several parts is the score. Representative: Divide a whole into five parts on average, and take two of them. Representation: divide a whole into four parts on average and take one of them.

2, the method of comparing sizes: the numerator is the same, and the score with a small denominator is large. The denominator is the same: the higher the numerator, the higher the score.

3. Add and subtract fractions with the denominator. The denominator remains the same, and only the numerator is added and subtracted.

The denominator means to divide a whole into several parts on average, and the numerator means to take several parts.

5. In the ID code, the 17th code indicates gender: odd male and even female.

6. For items A and B, only items A and C can be B, namely meeting A and meeting B. Find the total number of people: A+B-C How many people are there in meeting A or meeting B: A+B–C–C or (A–C)+(B–C).

7. When a small square is used to form a rectangle or a square, the shorter the length and width (or the same length and width), the shorter the circumference.

8. Features of quadrilateral: It has four straight sides and four corners.

9. The characteristics of a rectangle: the opposite sides are equal and there are four right angles.

10, the characteristics of a square: all four sides are equal and there are four right angles.

1 1. The length of a closed graph is its perimeter.

12, perimeter of rectangle = (length+width) ×2 perimeter of square = side length× 4.

13. Cut out the largest square in the rectangle, and the width of the rectangle is the side length of the square.