How come we are in the 21st century if we are in the 2000s and not 2100s?

100 views

How come we are in the 21st century if we are in the 2000s and not 2100s?

In: Other

0001-0099 is the first century. 0100-0199 is the 2nd century. etc and so on. so 2000-2099 is the 21st century.

Because our modern calendar starts with the year 1 AD. This means that the *first* century went from 1 AD to 100 AD. The *second* century was 101 – 200. Third = 201 – 300. Keep going down the line, and you see that 21st = 2001 – 2100.

1 AD to 99 AD was the 1st century so the 100s are the 2nd century and so on until 2000s which are the 21st century.

The first century went from the year 1 to the year 100, so the 2nd century was from 101 to 200, which mean the 21st century s from 2001 to 2100.

The first century CE would have been from 000-099 CE. So 0100-0199 CE would have been the second century and 1000-1099 the eleventh.

Edit: made a whoopsie

If you consider the last year of each century, it starts to become a lot more intuitive!

​

1st century: year 1 to year 100 –>100:100 = 1

2nd century: year 101 to year 200 –> 200:100 = 2

20th century: year 1901 to year 2000 –> 2000/100 = 20

21st century: year 2000 to year **2100** –> 2100/100 = 21

The day from your birth up to your first birthday is your first year on earth.

So [0, 1) is your first year.

[0, 10) is your first decade

[0, 100) is your first century

[100, 200) your second century

[2000, 2100) your twenty-first century

Now apply this to a calendar instead of your birthday and you have your answer:

The number marks the years that have – passed – while the term “21st century” marks the time span that is – going on currently.

**Please read this entire message**

Your submission has been removed for the following reason(s):

* ELI5 requires that you *search the ELI5 subreddit for your topic before posting*.

Users will often either find a thread that meets their needs or find that their question might qualify for an exception to rule 7.

Please see this [wiki entry](http://www.reddit.com/r/explainlikeimfive/wiki/how_to_search) for more details (Rule 7).


If you would like this removal reviewed, please read the [detailed rules](https://www.reddit.com/r/explainlikeimfive/wiki/detailed_rules) first. **If you believe this submission was removed erroneously**, please [use this form](https://old.reddit.com/message/compose?to=%2Fr%2Fexplainlikeimfive&subject=Please%20review%20my%20thread?&message=Link:%20https://www.reddit.com/r/explainlikeimfive/comments/ncckve/-/Please%20answer%20the%20following%203%20questions:1.%20The%20concept%20I%20want%20explained:2.%20Link%20to%20the%20search%20you%20did%20to%20look%20for%20past%20posts%20on%20the%20ELI5%20subreddit:3.%20How%20is%20this%20post%20unique🙂 and we will review your submission.


Other Questions You Might Be Interested In: