The concept of a decade in the modern world is not common, but you need to know it in order to freely navigate in time and have an idea of the duration of socially important events. A decade is a period of time that lasts ten days or ten years. From signs and announcements you can find out about the upcoming decade of the development of languages, at work stumble upon a report on the spent decade of psychology, and at school get acquainted with the analysis of the decade of the natural-mathematical cycle.
Decade is a concept known since ancient times.
The word "decade" came to us from antiquity and then literally meant "ten." This concept was present in ancient culture. Later it was transferred from Latin and Greek to modern European languages. Thus, the meaning of the word “ten” has been preserved, and it is no coincidence that the word “ten” of the Russian language is consonant with “decade,” a word borrowing from the Greek language.
European languages are also no exception. Despite the difference in spelling and some differences in sound, the common Indo-European root, from which the word “decade” was formed, can be distinguished in many modern languages of Europe. In German, "ten" is zehn, in English ten, in French - dix.
The origin of the decade and today's use of this concept
The Pythagoreans considered the number 10 magic and attached great importance to it. In addition, people always understood that it was more convenient to count, taking the decimal number system as a basis .
Today it is customary to divide the month into weeks, and the basis of this division is the number 7. Decade is the third of the month, that is, it implies a time period of ten days. During the French Revolution, it was decided to introduce a calendar using a ten-day unit of measure. This greatly facilitated and simplified the perception of time, because it is easier to break a month into ten units than seven.
But still a decade is how much: ten days or ten years? In modern Russian, a decade is most often used in its first meaning. When a decade appears in a speech, one usually refers to one of the three decades of a certain month (for example, the first decade of March, the second decade of September, etc.) But, in principle, one can also define such a concept as a decade of the year. To calculate it, you need to divide the total number of days in a year (365 or 366 days) by 10, get the total number of decades (36.5 or 36.6) and select the year of interest.
So, despite the relatively rare use of this unit of time, it involves some convenience for those involved in mathematics, physics, electronics, economics, operates with statistical and any other numerical data. The knowledge of the term is necessary for every person for a good orientation in the realities of the modern world.