Question

why do we call this century as 21st century and not 20th century even though its the 2000s??

Answer 1

We call this century as the 21st century because

From 0AD to 100AD was the 1st century

From 100 to 200 was the 2nd century

And so on.

As we can see here, for the 100s, it is called the 2nd century

Similarly for the 2000s, it can be calculated to be the 21st century

In a line- Often, when we calculate such a situation, we tend to forget the 1st century, so we miss out on the 1 century which occured first.

Good luck mate!

Answer 2

The 21st (twenty-first) century is the current century of the Anno Domini era or Common Era, in accordance with the Gregorian calendar. It began on January 1, 2001, and will end on December 31, 2100. ... It is distinct from the century known as the 2000s which began on January 1, 2000 and will end on December 31, 2099.