84
84 is a composite number, even, a calendar year.
Historical context — 84 AD
Calendar year
AD 84 (LXXXIV) was a leap year starting on Thursday of the Julian calendar.
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Historical context — 84 BC
Calendar year
Year 84 BC was a year of the pre-Julian Roman calendar.
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Year facts
- Year type
-
Leap year
Divisible by 4 and not by 100; February has 29 days.
- Days in year
- 366
- ISO weeks
- 52
- Started on
-
Saturday
January 1, 84
- Ended on
-
Sunday
December 31, 84
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
80s
80–89
- Century
-
1st century
1–100
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,942
1942 years before 2026.
In other calendars
- Hebrew
-
3844 / 3845 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Wood zodiac:Monkey
Sexagenary cycle position 21 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
627 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
76 / 77 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
6 / 5 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 2 2 × 3 × 7
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- eighty-four
- Ordinal
- 84th
- Roman numeral
- LXXXIV
- Binary
- 1010100
- Octal
- 124
- Hexadecimal
- 0x54
- Base64
- VA==
- One's complement
- 171 (8-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹 𒌋𒌋𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺
- Greek (Milesian)
- πδʹ
- Mayan (base 20)
- 𝋤·𝋤
- Chinese
- 八十四
- Chinese (financial)
- 捌拾肆
Digit at this position in famous constants
- π — Pi (π)
- Digit 84 = 2
- e — Euler's number (e)
- Digit 84 = 7
- φ — Golden ratio (φ)
- Digit 84 = 0
- √2 — Pythagoras's (√2)
- Digit 84 = 5
- ln 2 — Natural log of 2
- Digit 84 = 0
- γ — Euler-Mascheroni (γ)
- Digit 84 = 3
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 84, here are decompositions:
- 5 + 79 = 84
- 11 + 73 = 84
- 13 + 71 = 84
- 17 + 67 = 84
- 23 + 61 = 84
- 31 + 53 = 84
- 37 + 47 = 84
- 41 + 43 = 84
Showing the first eight; more decompositions exist.
As an ASCII codepoint, 84 is T. Printable ASCII character T.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.84.
- Address
- 0.0.0.84
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.84
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Matches numbered highway designation:
- I-84 — Two segments: Portland, OR→Echo, UT and Scranton, PA→Sturbridge, MA.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.