What is the math knowledge about the Spring Festival?

The mathematical knowledge about the Spring Festival is as follows:

1. There are 365 days in the solar calendar and 354 or 355 days in the lunar calendar. The date of the Spring Festival every year is about 365-354= 1 1 (days) earlier than the previous year.

It will be more convenient to calculate the date of Spring Festival with a clock plate. First fix the pointer on the date of this year's Spring Festival, and then turn the pointer counterclockwise 1 1 to know the approximate date of next year's Spring Festival.

3. The mathematical problem of fireworks packaging is perimeter. Take 2×2 fireworks packaging as an example, four arcs are pieced together into a circle, and the length of 1 blue line segment is just the diameter of the circle, so the circumference of the outer circle = the circumference of the circle+the diameter of the circle.

4. Most of the fireworks used in the party are high-altitude fireworks, which can fly to the height of 100 to 200 meters. The radius of a fireworks bomb with a radius of 20 cm ~ 30 cm is about 80 m ~ 100 m after explosion.

5. Send New Year's greetings. Xiao Ming cut out a square piece of paper with a side length of 1 m, which is 25 cm away from the apex and along a 45-degree angle, forming a small square in the middle, and wrote the five characters "Congratulations on making a fortune" and "Fu" in the picture. The area of the small square with the word "Fu" written in the middle is 2× 0.25× 0.25 = 0.1.25m2. ..