309
309 is a composite number, odd, a calendar year.
309 (three hundred nine) is an odd 3-digit number. It is a composite number with 4 divisors, and factors as 3 × 103. Written other ways, in Roman numerals it is CCCIX and in binary, 100110101.
Interestingness
Historical context — 309 AD
Calendar year
Year 309 (CCCIX) was a common year starting on Saturday of the Julian calendar.
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Historical context — 309 BC
Calendar year
Year 309 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
- 52
- Started on
-
Friday
January 1, 309
- Ended on
-
Friday
December 31, 309
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
300s
300–309
- Century
-
4th century
301–400
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,717
1717 years before 2026.
In other calendars
- Hebrew
-
4069 / 4070 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Earth zodiac:Snake
Sexagenary cycle position 6 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
852 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
301 / 302 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
231 / 230 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 × 103
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√309 = [17; (1, 1, 2, 1, 2, 4, 1, 1, 1, 8, 6, 1, 10, 1, 6, 8, 1, 1, 1, 4, 2, 1, 2, 1, …)]
Period length 26 — the block in parentheses repeats forever.
Representations
- In words
- three hundred nine
- Ordinal
- 309th
- Roman numeral
- CCCIX
- Binary
- 100110101
- Octal
- 465
- Hexadecimal
- 0x135
- Base64
- ATU=
- One's complement
- 65,226 (16-bit)
- Scientific notation
- 3.09 × 10²
- As a duration
- 309 s = 5 minutes, 9 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- τθʹ
- Mayan (base 20)
- 𝋯·𝋩
- Chinese
- 三百零九
- Chinese (financial)
- 參佰零玖
Digit at this position in famous constants
- π — Pi (π)
- Digit 309 = 0
- e — Euler's number (e)
- Digit 309 = 6
- φ — Golden ratio (φ)
- Digit 309 = 4
- √2 — Pythagoras's (√2)
- Digit 309 = 9
- ln 2 — Natural log of 2
- Digit 309 = 0
- γ — Euler-Mascheroni (γ)
- Digit 309 = 3
Also seen as
UTF-8 encoding: C4 B5 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.1.53.
- Address
- 0.0.1.53
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.1.53
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 309 is an active NANP area code (North American Numbering Plan).
- Primary area
- Peoria / Bloomington
- Region
- Illinois
- Country
- United States
Most NANP area codes have multiple overlays in dense regions; the primary area listed is the historic/largest population center for this code.
Heard as a frequency, 309 Hz is closest to:
- Concert pitch (A4 = 440 Hz): D♯4 (311.1 Hz, -12¢)
- Scientific pitch (C4 = 256 Hz): D♯4 (304.4 Hz, +26¢)
- Baroque pitch (A4 = 415 Hz): E4 (310.9 Hz, -11¢)
Related reading
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.