285
285 is a composite number, odd, a calendar year.
285 (two hundred eighty-five) is an odd 3-digit number. It is a composite number with 8 divisors, and factors as 3 × 5 × 19. Written other ways, in Roman numerals it is CCLXXXV and in binary, 100011101.
Interestingness
Historical context — 285 AD
Calendar year
The year 285 (CCLXXXV) was a common year starting on Thursday of the Julian calendar.
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Historical context — 285 BC
Calendar year
Year 285 BC was a year of the pre-Julian Roman calendar.
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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
-
53
Long year: contains 53 ISO weeks.
- Started on
-
Thursday
January 1, 285
- Ended on
-
Thursday
December 31, 285
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Decade
-
280s
280–289
- Century
-
3rd century
201–300
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,741
1741 years before 2026.
In other calendars
- Hebrew
-
4045 / 4046 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Wood zodiac:Snake
Sexagenary cycle position 42 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
828 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
277 / 278 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
207 / 206 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 × 5 × 19
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√285 = [16; (1, 7, 2, 7, 1, 32)]
Period length 6 — the block in parentheses repeats forever.
Representations
- In words
- two hundred eighty-five
- Ordinal
- 285th
- Roman numeral
- CCLXXXV
- Binary
- 100011101
- Octal
- 435
- Hexadecimal
- 0x11D
- Base64
- AR0=
- One's complement
- 65,250 (16-bit)
- Scientific notation
- 2.85 × 10²
- As a duration
- 285 s = 4 minutes, 45 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- σπεʹ
- Mayan (base 20)
- 𝋮·𝋥
- Chinese
- 二百八十五
- Chinese (financial)
- 貳佰捌拾伍
Digit at this position in famous constants
- π — Pi (π)
- Digit 285 = 9
- e — Euler's number (e)
- Digit 285 = 0
- φ — Golden ratio (φ)
- Digit 285 = 5
- √2 — Pythagoras's (√2)
- Digit 285 = 0
- ln 2 — Natural log of 2
- Digit 285 = 3
- γ — Euler-Mascheroni (γ)
- Digit 285 = 9
Also seen as
UTF-8 encoding: C4 9D (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.1.29.
- Address
- 0.0.1.29
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.1.29
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 285 Hz is closest to:
- Concert pitch (A4 = 440 Hz): C♯4 (277.2 Hz, +48¢ — about midway to D4)
- Scientific pitch (C4 = 256 Hz): D4 (287.4 Hz, -14¢)
- Baroque pitch (A4 = 415 Hz): D4 (277 Hz, +49¢ — about midway to D♯4)
Related reading
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.