What Decade Is It?

[Spexxvet]

Originally Posted by Radar

Dana, imagine you're a 9 year old kid. From the moment you were born until your first birthday they referred to your age as months. You had not reached a year yet. After a full year had passed, they referred to you as 1 year old.

If you are a 9 year old kid, and your 10th birthday is approaching. On your birthday, you have reached the end of your first decade because at this point you have lived 10 full years.

0 to 1
1 to 2
2 to 3
3 to 4
4 to 5
5 to 6
6 to 7
7 to 8
8 to 9
9 to 10


10 = 10 years have passed = 1 decade.

100 = 100 years have passed = 1 century

1000 = 1000 years have passed = 1 millennium

2000 = 2000 years have passed = 2 millennium

This means 1900 was the last year of the 19th century. 1901 was the first year of the 20th century.

2000 was the last year of the 2nd millennium and 2001 was the first year of the 21st century.

If:

Originally Posted by Radar

0 to 1
1 to 2
2 to 3
3 to 4
4 to 5
5 to 6
6 to 7
7 to 8
8 to 9
9 to 10

Then 1899 to 1900 was the last year of the 19th century. It ended, technically, on Dec. 31, 1899.

Not:

Originally Posted by Radar

This means 1900 was the last year of the 19th century. 1901 was the first year of the 20th century.

2000 was the last year of the 2nd millennium and 2001 was the first year of the 21st century.