How many years is a decade, century, millennium?

The time markers of a decade, a century, a millennium are very familiar to everyone because they appear in daily life, appearing everywhere. And it is also very easy to come across phrases like the 19th century, the 80s, or going through a millennium. So how many years do these time markers represent?

How many years are in a millennium, century, or decade?

According to the Gregorian calendar convention, also known as the Gregorian calendar, time milestones are conventionally divided into years:

• 1 millennium = 10 centuries = 1000 years
• 1 century = 10 decades = 100 years.
• 1 decade = 10 years = 3652 days.

There are three different ways to calculate the millennium .

Method 1: 1 millennium is calculated from year x001 - y002, that is, millennium I is calculated from year 1 to year 1010, millennium II starts from year 1002 to 2002.

Method 2: A millennium is calculated from year x000 - x999, meaning from 1000-1999 is millennium 1000, from 2000-2999 is called millennium 2000.

Method 3: 1 millennium is calculated from year x001 - y000, meaning the 1st millennium is from year 1 AD - 1000 AD, the 2nd millennium starts from year 1001 - 2000, the 3rd millennium starts from year 2001 - 3000.

According to this calculation, 2024 is the 24th year of the 3rd millennium and of the 21st century and the fifth year of the 2020s.

The formula for calculating centuries is simpler n = 100xn – 99. Century 1 is from 1/1/1 to 12/31/100, century 2 is from year 101 and ends in year 200.

The 21st century began on January 1, 2001 and ends on December 31, 2100. The year 2020 belongs to the 21st century.

The formula for calculating a decade is based on two viewpoints. One viewpoint holds that a decade starts from the year ending in 0 and ends in the year ending in 9, for example, the 80s of the 20th century were from 1980 to 1989, and 2020 belongs to the 20s of the 21st century.

Another view is that a decade starts with the year ending in 1 and ends with the year ending in 0. For example, the 10s of the 19th century started from 2011 to 2020, so 2020 is the last year of this decade.

Of course, counting 2020 as the beginning of a new decade or the last year of a decade does not affect life too much and also depends on each person's calculation.

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