Decade

=== 1-to-0 decade ===
A rarer approach groups years from the beginning of the [[Anno Domini|AD calendar era]] to produce successive decades from a year ending in a 1 to a year ending in a 0, with the years 1–10 described as "the 1st decade", years 11–20 "the 2nd decade", and so on; later decades are more usually described as 'the st, nd, rd, or th decade of the st, nd, rd, or th century' (using the [[century|strict interpretation of 'century']]).{{efn| name = century}} For example, "the second decad of the 12th. Cent." {{sic}};<ref>{{cite book |last1=1837 HALLAM Hist. Lit. I. i. 19 |title=The Compact Edition of the Oxford English Dictionary }}</ref> "The last decade of that century";<ref>{{cite book |last1=1878 DOWDEN Stud. Lit. I |title=The Compact Edition of the Oxford English Dictionary }}</ref> "1st decade of the 16th century";<ref>{{cite web |title=Catalogue of Illuminated Manuscripts |url=https://www.bl.uk/catalogues/illuminatedmanuscripts/results.asp?AttribID=228 |website=British Library |access-date=24 February 2020 |archive-date=29 June 2022 |archive-url=https://web.archive.org/web/20220629043437/https://www.bl.uk/catalogues/illuminatedmanuscripts/results.asp?AttribID=228 |url-status=dead }}</ref> "third decade of the 16th century";<ref>{{cite web |title=Illuminated Manuscripts from the Collection of Maurice Burrus (1882–1959) |url=https://www.christies.com/lotfinder/Lot/book-of-hours-use-of-paris-in-5994394-details.aspx |website=CHRISTIE'S |access-date=24 February 2020}}</ref> "the first decade of the 18th century".<ref>{{cite web |title=French harpsichord music in the first decade of the 18th century |url=https://academic.oup.com/em/article-abstract/XVII/2/184/352150?redirectedFrom=PDF |website=Oxford Academic |access-date=24 February 2020}}</ref> This decade grouping may also be identified explicitly; for example, "1961–1970";<ref>{{cite web |title=Past Poets Laureate: 1961–1970 |url=https://www.loc.gov/poetry/laureate-1961-1970.html |website=The Library of Congress |access-date=24 February 2020}}</ref> "2001–2010";<ref>{{cite web |title=Milestones 2001–2010 |url=https://www.un.org/en/sections/history/milestones-2001-2010/index.html |website=United Nations |access-date=24 February 2020}}</ref> "2021–2030".<ref>{{cite web |title=Solar Eclipses: 2021–2030 |url=https://eclipse.gsfc.nasa.gov/SEdecade/SEdecade2021.html |website=NASA |access-date=24 February 2020}}</ref> The BC calendar era ended with the year 1{{nbs}}BC and the AD calendar era began the following year, AD{{nbs}}1. There was no year 0.

{| class="wikitable"
|+ Usage methods compared
!Year
|1
|2
|3
|...
|9
|10
|11
|12
|...
|19
|20
|...
|2000
|2001
|2002
|...
|2009
|2010
|2011
|2012
|...
|2019
|2020
|2021
|2022
|...
|2029
|2030
|-
!0-to-9 decade
| colspan="5" style="background: #fef6e7; text-align: center;" |[[0s]]
| colspan="5" style="background: #fef6e7; text-align: center;" |[[10s]]
| colspan="2" style="text-align: center;" |...
| colspan="5" style="background: #fef6e7; text-align: center;" |[[2000s (decade)|2000s]]
| colspan="5" style="background: #fef6e7; text-align: center;" |[[2010s]]
| colspan="5" style="background: #fef6e7; text-align: center;" |[[2020s]]
| style="text-align: center;" |...
|-
!1-to-0 decade
| colspan="6" style="background: #eaeaff; text-align: center;" |1st decade of the 1st century
| colspan="5" style="background: #eaeaff; text-align: center;" |2nd decade of the 1st century
| colspan="2" style="text-align: center;" |...
| colspan="5" style="background: #eaeaff; text-align: center;" |1st decade of the 21st century
| colspan="5" style="background: #eaeaff; text-align: center;" |2nd decade of the 21st century
| colspan="5" style="background: #eaeaff; text-align: center;" |3rd decade of the 21st century
|}