Formula: left scale × number of beads = right scale × number of beads.

Demonstration: left scale (3)× number of beads (4)= right scale (6)× number of beads (2)

2. Design a sports ground (difficulty: ordinary) P: This can only be practiced by yourself!

Methods: First calculate the sum of two straight runways, and then calculate the perimeter of two semicircles (equal to a circle). P: We can't divide the circumference of a circle by two, so we should keep two decimal places. ..... This is to find the length of the trajectory.

Find the area of the middle rectangular ground (length × circle diameter). Find the area of two semicircles (equal to a circle).

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3. Knowledge in stamps (difficulty: simple) P: You must remember the formula before you can use it freely!

Local port: 1g~ 100g per 20g (20g is counted as a part of 20g) 0.8 yuan.

10 1g and above 100g( 100g and below 100g) 1.2 yuan.

Field: 1g~ 100g per 20g(20g for 20g) 1.2 yuan.

10 1g and above 100g( 100g and below 100g) 1.6 yuan.

Hope to help you, hope to adopt!