Editing Common year starting on Friday

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A '''common year starting on Friday''' is any non-[[leap year]] (i.e. a year with 365 days) that begins on [[Friday]], 1 January, and ends on Friday, 31 December. Its [[dominical letter]] hence is '''C'''. The most recent year of such kind was [[2021]], and the next one will be [[2027]] in the [[Gregorian calendar]],<ref name="math">{{cite web|url=https://webspace.science.uu.nl/~gent0113/calendar/isocalendar.htm |author=Robert van Gent |title=The Mathematics of the ISO 8601 Calendar |publisher=Utrecht University, Department of Mathematics |date=2017 |access-date=20 July 2017}}</ref> or, likewise, [[2022]] and [[2033]] in the obsolete [[Julian calendar]]; see [[#Applicable years|below for more]]. This common year is one of the three possible common years in which a century year can end on, and occurs in century years that [[Century common year|yield a remainder of 100 when divided by 400]]. The most recent such year was [[1700]], and the next one will be [[2100]].

Any common year that starts on [[Friday]] has only one [[Friday the 13th]]: the only one in this common year [[August 13|occurs in August]]. [[Leap year starting on Thursday|Leap years starting on Thursday]] share this characteristic, but also have another one [[February 13|in February]].

From [[July]] of the year that precedes this type of year until [[September]] in this type of year is the longest period (14 months) that occurs without a [[Friday the 13th #Friday the 17th in Italy|Friday the 17th]]. [[Leap years starting on Tuesday]] share this characteristic, from [[August]] of the [[common year starting on Monday|common year that precedes it]] to [[October]] in that type of year). This type of year also has the longest period (also 14 months) without a [[Tuesday the 13th]], from July of this year until September of the next common year (that being on [[Common year starting on Saturday|Saturday]]), unless the next year is a leap year (which is also a [[Leap year starting on Saturday|Saturday]]), then the period is reduced to only 11 months.

From [[February]] until [[March]] in this type of year is also the shortest period (one month) that runs between two months that begin exactly on the first day of the week, in areas where Monday is regarded the first day  of the week.

This is the one of two types of years overall where a [[perfect month|rectangular February]] is possible, in places where Monday is considered to be the first day of the week. [[Common year starting on Thursday|Common years starting on Thursday]] share this characteristic, when Sunday is considered to be the first day of the week.

Additionally, this type of year has three months (February, March and November) beginning exactly on the first day of the week, in areas which Monday is considered the first day of the week. [[Leap years starting on Monday]] share this characteristic on the months of January, April and July.

== Calendars ==
<!-- To avoid arbitrary years, use the most recent year of this type. 2021 was the most recent year of this type. -->
{{calendar|year=2021|show_year=off|title=Calendar for any [[common year]] starting on Friday,<br />presented as common in many English-speaking areas}}

{{calendar|year=2021|show_year=off|format=iso|row=3|zero=0|title=[[ISO 8601]]-conformant calendar with [[ISO week date|week numbers]] for<br />any common year starting on Friday (dominical letter C)}}

This is the only year type where the ''n''th "[[Doomsday (weekday)|Doomsday]]" (this year Sunday) is not in ISO week ''n''; it is in ISO week ''n''-1.

== Applicable years ==
=== Gregorian calendar ===
In the (currently used) Gregorian calendar, alongside [[Common year starting on Sunday|Sunday]], [[Common year starting on Monday|Monday]], [[Common year starting on Wednesday|Wednesday]] or [[Common year starting on Saturday|Saturday]], the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-three common years per cycle or exactly 10.75% start on a Friday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.

For this kind of year, the ISO week 10 (which begins March 8) and all subsequent ISO weeks occur later than in all other years, and exactly one week later than [[Leap year starting on Thursday|Leap years starting on Thursday]]. Also, the ISO weeks in January and February occur later than all other common years, but [[Leap year starting on Friday|leap years starting on Friday]] share this characteristic in January and February, until ISO week 8.
{| class="wikitable"
|+ Gregorian common years starting on Friday<ref name="math" />
!scope=row| Decade
! 1st !!colspan=2| 2nd !!colspan=2| 3rd !! 4th !!colspan=2| 5th !! 6th !! 7th !!colspan=2| 8th !! 9th !!colspan=2| 10th
|-
! [[16th century]]
|colspan=12| ''prior to first adoption (proleptic)'' || [[1582]] || [[1593]] || [[1599]]
|-
! [[17th century]]
| [[1610]] ||colspan=2| — || [[1621]] || [[1627]] || [[1638]] ||colspan=2| [[1649]] || [[1655]] || [[1666]] ||colspan=2| [[1677]] || [[1683]] || [[1694]] || [[1700]]
|-
! [[18th century]]
| [[1706]] ||colspan=2| [[1717]] ||colspan=2| [[1723]] || [[1734]] ||colspan=2| [[1745]] || [[1751]] || [[1762]] || [[1773]] || [[1779]] || [[1790]] ||colspan=2| —
|-
! [[19th century]]
| [[1802]] || [[1813]] || [[1819]] ||colspan=2| [[1830]] || — || [[1841]] || [[1847]] || [[1858]] || [[1869]] ||colspan=2| [[1875]] || [[1886]] ||colspan=2| [[1897]]
|-
! [[20th century]]
| [[1909]] ||colspan=2| [[1915]] ||colspan=2| [[1926]] || [[1937]] ||colspan=2| [[1943]] || [[1954]] || [[1965]] ||colspan=2| [[1971]] || [[1982]] || [[1993]] || [[1999]]
|-
! [[21st century]]
|  –  ||colspan=2|[[2010]] || [[2021]] || [[2027]] || [[2038]] ||colspan=2| [[2049]] || [[2055]] || [[2066]] ||colspan=2| [[2077]] || [[2083]] || [[2094]] || [[2100]]
|-
! [[22nd century]]
| [[2106]] ||colspan=2| [[2117]] ||colspan=2| [[2123]] || [[2134]] ||colspan=2| [[2145]] || [[2151]] || [[2162]] || [[2173]] || [[2179]] || [[2190]] ||colspan=2| —
|-
! [[23rd century]]
| [[2202]] || [[2213]] || [[2219]] ||colspan=2| [[2230]] || — || [[2241]] || [[2247]] || [[2258]] || [[2269]] ||colspan=2| [[2275]] || [[2286]] ||colspan=2| [[2297]]
|-
! [[24th century]]
| [[2309]] ||colspan=2| [[2315]] ||colspan=2| [[2326]] || [[2337]] ||colspan=2| [[2343]] || [[2354]] || [[2365]] ||colspan=2| [[2371]] || [[2382]] || [[2393]] || [[2399]]
|}

{| class="wikitable"
|+ 400-year cycle
|-
! 0–99
| 10 || 21 || 27 || 38 || 49 || 55 || 66 || 77 || 83 || 94 ||
|-
! 100–199
| 100 || 106 || 117 || 123 || 134 || 145 || 151 || 162 || 173 || 179 || 190
|-
! 200–299
| 202 || 213 || 219 || 230 || 241 || 247 || 258 || 269 || 275 || 286 || 297
|-
! 300–399
| 309 || 315 || 326 || 337 || 343 || 354 || 365 || 371 || 382 || 393 || 399
|}

=== Julian calendar ===
In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a [[solar cycle (calendar)|28-year cycle]] (1461 weeks). This sequence occurs exactly once within a cycle, and every common letter thrice.

As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 4, 15 and 26 of the cycle are common years beginning on Friday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Friday.

{| class="wikitable"
|+ Julian common years starting on Friday
!scope=row| Decade
!colspan=2| 1st !!colspan=2| 2nd !!colspan=2| 3rd !!colspan=2| 4th !!colspan=2| 5th !!colspan=2| 6th !!colspan=2| 7th !!colspan=2| 8th !!colspan=2| 9th !!colspan=2| 10th
|-
! 15th century
|colspan=2| [[1406]] ||colspan=2| [[1417]] ||colspan=2| [[1423]] ||colspan=2| [[1434]] ||colspan=2| [[1445]] ||colspan=2| [[1451]] ||colspan=2| [[1462]] || [[1473]] || [[1479]] ||colspan=2| [[1490]] ||colspan=2| —
|-
! 16th century
| [[1501]] || [[1507]] ||colspan=2| [[1518]] ||colspan=2| [[1529]] ||colspan=2| [[1535]] ||colspan=2| [[1546]] ||colspan=2| [[1557]] ||colspan=2| [[1563]] ||colspan=2| [[1574]] ||colspan=2| 1585 ||colspan=2| 1591
|-
! 17th century
|colspan=2| 1602 || 1613 || 1619 ||colspan=2| 1630 ||colspan=2| — || 1641 || 1647 ||colspan=2| 1658 ||colspan=2| 1669 ||colspan=2| 1675 ||colspan=2| 1686 ||colspan=2| 1697
|-
! 18th century
|colspan=2| 1703 ||colspan=2| 1714 ||colspan=2| 1725 ||colspan=2| 1731 ||colspan=2| 1742 || 1753 || 1759 ||colspan=2| 1770 ||colspan=2| — || 1781 || 1787 ||colspan=2| 1798
|-
! 19th century
|colspan=2| 1809 ||colspan=2| 1815 ||colspan=2| 1826 ||colspan=2| 1837 ||colspan=2| 1843 ||colspan=2| 1854 ||colspan=2| 1865 ||colspan=2| 1871 ||colspan=2| 1882 || 1893 || 1899
|-
! 20th century
|colspan=2| 1910 ||colspan=2| — || 1921 || 1927 ||colspan=2| 1938 ||colspan=2| 1949 ||colspan=2| 1955 ||colspan=2| 1966 ||colspan=2| 1977 ||colspan=2| 1983 ||colspan=2| 1994
|-
! 21st century
|colspan=2| 2005 ||colspan=2| 2011 ||colspan=2| 2022 || 2033 || 2039 ||colspan=2| 2050 ||colspan=2| — || 2061 || 2067 ||colspan=2| 2078 ||colspan=2| 2089 ||colspan=2| 2095
|}

== Holidays ==

=== International ===
* [[Valentine's Day]] falls on a [[Sunday]]
* [[Grandparents' Day|World Day for Grandparents and the Elderly]] falls on [[July 25]]
* [[Halloween]] falls on a [[Sunday]]. This is the only year when Halloween falls in ISO week 43. They fall in ISO week 44 in all other years.
* [[Christmas Day]] falls on a [[Saturday]]

=== Roman Catholic Solemnities ===
* [[Epiphany (holiday)|Epiphany]] falls on a [[Wednesday]]
* [[Candlemas]] falls on a [[Tuesday]]
* [[Saint Joseph's Day]] falls on a [[Friday]]
* The [[Annunciation of Jesus]] falls on a [[Thursday]]
* The [[Nativity of John the Baptist]] falls on a [[Thursday]]
* The [[Solemnity of Saints Peter and Paul]] falls on a [[Tuesday]]
* The [[Transfiguration of Jesus]] falls on a [[Friday]]
* The [[Assumption of Mary]] falls on a [[Sunday]]
* The [[Exaltation of the Holy Cross]] falls on a [[Tuesday]]
* [[All Saints' Day]] falls on a [[Monday]]
* [[All Souls' Day]] falls on a [[Tuesday]]
* The [[Feast of Christ the King]] falls on [[November 21]] (or on its latest possible date of [[October 31]] in versions of the calendar between 1925 and 1962)
* The [[First Sunday of Advent]] falls on [[November 28]]
* The [[Immaculate Conception]] falls on a [[Wednesday]]
* [[Gaudete Sunday]] falls on [[December 12]]
* [[Rorate Sunday]] falls on [[December 19]]

=== Australia and New Zealand ===
* [[Australia Day]] falls on a [[Tuesday]]
* [[Waitangi Day]] falls on a [[Saturday]]
* [[Daylight saving]] ends on [[April 4]]
* [[ANZAC Day]] falls on a [[Sunday]], and in some years coincides with [[Easter Sunday]] falling on its latest possible date
* [[Mother's Day]] falls on [[May 9]]
* [[Father's Day]] falls on [[September 5]]
* Daylight saving begins on [[September 26]] in New Zealand and [[October 3]] in Australia

=== British Isles ===
* [[Saint David's Day]] falls on a [[Monday]]
* [[Mother's Day]] falls on [[March 7]], [[March 14]], [[March 21]], [[March 28]] or on its latest possible date of [[April 4]]
* [[Daylight saving]] begins on [[March 28]]
* [[Saint Patrick's Day]] falls on a [[Wednesday]]
* [[Saint George's Day]] falls on a [[Friday]], and in some years coincides with [[Good Friday]] falling on its latest possible date
* [[Father's Day]] falls on [[June 20]]
* [[Orangeman's Day]] falls on a [[Monday]]
* [[Daylight saving]] ends on its latest possible date, [[October 31]]
* [[Guy Fawkes Night]] falls on a [[Friday]]
* [[Saint Andrew's Day]] falls on a [[Tuesday]]

=== Canada ===
* [[Daylight saving]] begins on its latest possible date, [[March 14]]
* [[Mother's Day]] falls on [[May 9]]
* [[Victoria Day]] falls on its latest possible date, [[May 24]]
* [[Father's Day]] falls on [[June 20]]
* [[Canada Day]] falls on a [[Thursday]]
* [[Labour Day (Canada)|Labour Day]] falls on [[September 6]]
* [[Thanksgiving Day (Canada)|Thanksgiving Day]] falls on [[October 11]]
* Daylight saving ends on its latest possible date, [[November 7]]

=== United States ===
* [[Martin Luther King Jr. Day]] falls on [[January 18]]
* [[President's Day]] falls on its earliest possible date, [[February 15]]
* [[Daylight saving]] begins on its latest possible date, [[March 14]]
* [[Mother's Day]] falls on [[May 9]]
* [[Memorial Day]] falls on its latest possible date, [[May 31]]
* [[Juneteenth]] falls on a [[Saturday]]
* [[Father's Day]] falls on [[June 20]]
* [[Independence Day (United States)|Independence Day]] falls on a [[Sunday]]
* [[Labor Day (United States)|Labor Day]] falls on [[September 6]]
* [[Grandparents' Day]] falls on [[September 12]]
* [[Columbus Day]] falls on [[October 11]]
* Daylight saving ends on its latest possible date, [[November 7]]
* [[Thanksgiving Day]] falls on [[November 25]]

== References ==
{{Reflist}}
{{List of calendars}}
{{DEFAULTSORT:Common Year Starting On Friday}}
[[Category:Gregorian calendar]]
[[Category:Julian calendar]]
[[Category:Friday]]