What are the 10 examples of mathematics in life?

1. If we go to a wedding with more than 367 people, then there must be people with the same birthday (not the same year). Put m things into n empty drawers randomly (m>n), then there must be at least 2 things in one drawer. Since there are at most 366 days in a year, at least 2 of the 367 people were born on the same day of the same month. This is equivalent to putting 367 items into 366 drawers, with at least 2 items in the same drawer.

2. In winter, cats always hug their bodies into a ball shape when sleeping, because this way the body dissipates the least heat. In mathematics, the object with a given volume and the smallest surface area is a sphere. When a cat shrinks into a sphere, it can reduce the area in contact with the outside world, reduce the speed of heat exchange, reduce the speed of heat loss, save energy, and maintain body temperature.

3. "Müllereye illusion", also called arrow illusion. If two outward diagonal lines are added to both ends of one line segment, and two inward diagonal lines are added to both ends of another line segment, the former will appear much longer than the latter. There is a theory for this illusion, called the neural inhibition theory, which believes that when two contours are close to each other, adjacent nerve groups on the retina will inhibit each other, resulting in a displacement of the contours, creating an illusion.

4. The shape of the wheel is round. The center of a circle is called the center of the circle. The distance from any point on the circle to the center of the circle is equal. Make the wheel into a circle with the axle at the center of the circle. When the wheel rolls on the ground, the distance between the axle and the ground is always equal to the radius of the wheel. Therefore, people sitting in the car can be pulled by the car smoothly. If the wheel is deformed and is no longer round, one part of the wheel is higher than the other and the distance to the axle is unequal, the car will no longer be stable.

5. The fan blades are all odd numbers. This is because odd-numbered blade combinations can bring more performance advantages than even-numbered blade combinations.

If the number of blades is an even number and is arranged in a symmetrical manner, it will not only make it difficult to adjust the balance of the fan itself, but also easily cause the fan to produce more vibrations when rotating at high speed. Vibration causes the blades to be unable to withstand the fatigue caused by vibration for a long time, and eventually the blades break. Therefore, the design of axial flow fans is mostly an asymmetrical odd-numbered blade design.

The same design philosophy is reflected in the design of electric fans or propeller helicopters for everyday use. If the fan has a three-blade structure, the blades are made wider and the blade roots are stronger, and the density of each part must be uniform; if it is a five-blade structure, the blades are narrower and the thickness and strength are relatively low.

6. The winning probability of double color balls is low. The double-color ball is composed of 33 red balls and 16 blue balls. Each lottery draw basically maintains 6 red balls and 1 blue ball, so the winning rate of the first prize of the double-color ball is 1/17720000. In other words, the probability is one in ten million. Although the probability is very low, because our country's population base is very large and the number of people buying lottery tickets is relatively large, theoretically someone can win the first prize.

7. Four-leaf clover is called "lucky clover".

Clover, whose scientific name is alfalfa, is a perennial herbaceous plant. It generally has only three small leaves. The leaves are heart-shaped, and the darker part of the leaf center is also heart-shaped. The four-leaf clover is caused by a mutation in the clover gene, and it only accounts for one in 100,000 of them. In other words, among one hundred thousand alfalfa plants, you may only find one that is a 'four-leaf clover', because the chance is too small. Therefore, "four-leaf clover" is an internationally recognized symbol of luck.

8. Manhole covers are basically round.

This takes advantage of the fact that the diameters within the same circle are all equal. Only round manhole covers cannot find the diagonal, so no matter how the manhole cover is moved, the cover will not fall off, and the workers working below will be safe. If it is designed as a triangle or square, although the cover is larger than the manhole mouth, there is still a possibility of falling. In fact, in addition to safety, another advantage of making the manhole cover round is that it facilitates transportation.

9. Unforeseen circumstances arise.

This involves a mathematical definition - "chaos", which is "extreme instability to initial values." The common "butterfly effect" is a phenomenon of chaos. Under normal circumstances, global weather patterns basically follow certain known and reasonable processes. Through several different simulation methods and based on slightly different initial conditions, weather forecasters can predict future weather changes.

However, weather is composed of a complex combination of factors. Small changes in the initial conditions will make the forecast results vary greatly. At this time, the weather has entered the chaotic area. The longer the forecast time, the greater the possibility of reaching the chaotic point, so the accuracy of the weather forecast will be worse. grasp.

10. The golden section is 0.618.

0.618, an extremely fascinating and mysterious number, also known as the golden section, was discovered by Pythagoras, a famous ancient Greek mathematician, more than 2,500 years ago.

Once, Pythagoras passed by the blacksmith workshop and was fascinated by the tinkling sound of iron. To uncover the secrets hidden in this crisp and sweet sound. Pythagoras measured the dimensions of the hammer and anvil and found that there was a very harmonious proportional relationship between them.

When he returned home, he took out another piece of wire, divided it into two sections, compared them repeatedly, and finally decided that the ratio of 1:0.618 was the most beautiful.