Are there any other examples of 7's in life?

1, Tangrams:

The tangram is an ancient traditional Chinese intellectual toy, which, as the name suggests, is made up of seven boards. And these seven boards can be put together into many shapes (more than 1600 kinds), such as triangles, parallelograms, irregular polygons, and players can also put it together into all kinds of characters, images, animals, bridges, houses, towers, and so on, as well as some Chinese and English letters.

2, seven days a week:

Week, that is, a week. There are seven days in a week, which are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday.

The seven days were the cycle of the moon's waxing and waning. So, they divided a month into four weeks, seven days as a cycle, and respectively with the sun god (Sunday), the moon god (Monday), Mars god (Tuesday), Mercury god (Wednesday), Jupiter god (Thursday), Venus god (Friday), Saturn god (Saturday) seven star god for the seven days named, which is "the week" This is the earliest origin of the name "week".

3, seven basic levels:

In the musical system, the seven levels with independent names are called basic levels. These seven levels correspond to the sounds made by the white keys on the piano. The names of the basic levels are labeled by both tone names and chants, and the tone name of each level is labeled with a letter. The labeling of the seven basic levels (tone names and chanter names) is recycled in the musical tone system.

4, the seven colors of the rainbow:

When the sunlight shines on the water droplets in mid-air, the light is refracted and reflected, forming an arching seven-color spectrum in the sky, with seven colors from the outer circle to the inner circle: red, orange, yellow, green, blue, indigo and violet. In fact, there are countless colors in the rainbow, for example, there are many other nuances of color between red and orange, but for simplicity's sake, so only seven colors are used as a distinction.

5, the seven stars of the Big Dipper:

The seven stars of the Big Dipper, an important star in the sky of the northern hemisphere, consists of seven stars in the Ziwei Wall: Tianshu (Greedy Wolf), Tianxuan (Chuumen), Tiangui (Lukchun), Tianquan (Wencui), Yuhang (Lianzhen), Kaiyang (Wugu), and Shakuang (Breaking Army).

The seven stars of the Big Dipper were used by people in ancient times as a ruler to set directions, seasons and hours. The seven stars of the Big Dipper appeared in different directions in the sky at different times of the day and night, so the ancients decided the seasons according to the direction of the handle of the Big Dipper at the beginning of the twilight.