1,800
1,800 is a composite number, even, a calendar year.
Notable events — 1800 AD
- Apr 24 Congress authorizes the Library of Congress.
- Jun 14 Napoleon defeats the Austrians at Marengo.
- Nov 17 The US Congress holds its first session in Washington, D.C.
- Dec 3 Thomas Jefferson and Aaron Burr tie in the electoral college; the House decides for Jefferson in February.
- May 7 The Indiana Territory is organized.
Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0
Year facts
- Year type
-
Common year
Standard 365-day year; not divisible by 4 (or divisible by 100 but not 400).
- Days in year
- 365
- ISO weeks
- 52
- Started on
-
Wednesday
January 1, 1800
- Ended on
-
Wednesday
December 31, 1800
- Friday the 13ths
-
1
One Friday the 13th this year.
- Easter Sunday
-
April 13
Sunday, April 13, 1800
- Decade
-
1800s
1800–1809
- Century
-
18th century
1701–1800
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
226
226 years before 2026.
- US presidential election
-
Yes
US holds a presidential election in years divisible by 4 starting from 1788.
In other calendars
- Hebrew
-
5560 / 5561 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1214 / 1215 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Monkey
Sexagenary cycle position 57 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2343 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1178 / 1179 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1792 / 1793 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1722 / 1721 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 4
- Digit sum
- 9
- Digit product
- 0
- Digital root
- 9
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 81
- Flips to (rotate 180°)
- 81
- Recamán's sequence
- a(16,099) = 1,800
- Square (n²)
- 3,240,000
- Cube (n³)
- 5,832,000,000
- Divisor count
- 36
- σ(n) — sum of divisors
- 6,045
- φ(n) — Euler's totient
- 480
- Sum of prime factors
- 22
Primality
Prime factorization: 2 3 × 3 2 × 5 2
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand eight hundred
- Ordinal
- 1800th
- Roman numeral
- MDCCC
- Binary
- 11100001000
- Octal
- 3410
- Hexadecimal
- 0x708
- Base64
- Bwg=
- One's complement
- 63,735 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋 ·
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢
- Greek (Milesian)
- ͵αωʹ
- Mayan (base 20)
- 𝋤·𝋪·𝋠
- Chinese
- 一千八百
- Chinese (financial)
- 壹仟捌佰
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,800 = 8
- e — Euler's number (e)
- Digit 1,800 = 1
- φ — Golden ratio (φ)
- Digit 1,800 = 8
- √2 — Pythagoras's (√2)
- Digit 1,800 = 5
- ln 2 — Natural log of 2
- Digit 1,800 = 6
- γ — Euler-Mascheroni (γ)
- Digit 1,800 = 1
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1800, here are decompositions:
- 11 + 1789 = 1800
- 13 + 1787 = 1800
- 17 + 1783 = 1800
- 23 + 1777 = 1800
- 41 + 1759 = 1800
- 47 + 1753 = 1800
- 53 + 1747 = 1800
- 59 + 1741 = 1800
Showing the first eight; more decompositions exist.
UTF-8 encoding: DC 88 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.8.
- Address
- 0.0.7.8
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.7.8
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1800 first appears in π at position 23,738 of the decimal expansion (the 23,738ordinal-suffix:th digit after the integer 3).
Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.