86
"To 86" something is American diner and bar slang for getting rid of it, documented from the 1930s. 86 is also the atomic number of radon, the radioactive gas that seeps into buildings and is the leading cause of lung cancer in people who have never smoked.
- Even
- Composite
Where 86 fits
Why 86 is special
86's slang meaning — to discard, cancel, or refuse service — is documented in US diner and bar culture since the 1930s, though its precise origin is disputed.
Same number, different meanings
How 86 is understood across different contexts — never implying one meaning because of another.
- Mathematics
86's slang meaning — to discard, cancel, or refuse service — is documented in US diner and bar culture since the 1930s, though its precise origin is disputed.
- Everyday life
Element 86 is the reason homes are tested for radioactivity at all. Radon seeps from uranium-bearing rock into buildings, where it can accumulate in poorly ventilated ground floors and basements, and it is the leading cause of lung cancer in people who have never smoked. Testing is a cheap detector left in place for weeks, and remediation is usually a matter of ventilation rather than construction.
- Science
There are roughly 86 billion neurons in an adult human brain (adults, an estimate from isotropic fractionation). This replaced an older, widely repeated figure of 100 billion that had no clear primary source.
- Geography
+86 reaches China, the largest telephone network in the world by connections. It sits in the East Asian 8x block, and like most countries with very large networks its domestic numbers run longer than the international average.
- Culture
The American slang verb 'to 86' something or someone — meaning to discard, cancel, or refuse service to — is documented in US diner and bar culture from the 1930s, though its exact origin is disputed.
86 is part of
Factors & digit properties
- Divisors (4)
- 1, 2, 43, 86
- Prime factorisation
- 2 × 43
- Digit sum
- 14
- Digital root
- 5
Representations
- Decimal
- 86
- Scientific notation
- 8.600 × 10^1
Roman numerals
L X X X V I
Binary
1 0 1 0 1 1 0
1 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 1 × 2 + 0 × 1 = 86
Octal
1 2 6
1 × 64 + 2 × 8 + 6 × 1 = 86
Hexadecimal
5 6
5 × 16 + 6 × 1 = 86
Read as powers of two: 64 + 16 + 4 + 2 = 86.
In historical numeral systems
Egyptian
8 hobbles, 6 strokes
8 × 10 + 6 × 1 = 86. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 vertical wedge (sixties place), 2 corner wedges + 6 vertical wedges (units place)
1 × 60 + 26 = 86. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
pi, then stigma, marked as a numeral
pi-stigma + keraia
pi + stigma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
pe, then vav
pe-vav
pe (80) + vav (6) = 86, written in descending order.
Chinese numerals
bā shí liù
bā shí liù
八 before 十 multiplies it: 8 tens. 六 after it adds 6. The written form mirrors the arithmetic — "bā shí liù". The financial (anti-fraud) form is 捌拾陸.
Maya
4 dots (upper, twenties place) over 1 bar + 1 dot (lower, units place)
4 × 20 + 6 = 86. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
- Happy number
- Semiprime
Related numbers & connections
43 is a factor of 86 (43 × 2 = 86).
View 43 →Mongolia borders China and Russia and is the most sparsely populated sovereign state in the world.
View 976 →China's ISO numeric code and its calling code. The two were assigned by different bodies decades apart, which is why neither is derivable from the other.
View 156 →Everyday life
Element 86 is the reason homes are tested for radioactivity at all. Radon seeps from uranium-bearing rock into buildings, where it can accumulate in poorly ventilated ground floors and basements, and it is the leading cause of lung cancer in people who have never smoked. Testing is a cheap detector left in place for weeks, and remediation is usually a matter of ventilation rather than construction.
DocumentedEveryday life
Science
There are roughly 86 billion neurons in an adult human brain (adults, an estimate from isotropic fractionation). This replaced an older, widely repeated figure of 100 billion that had no clear primary source.
DocumentedScienceGeography: adults, an estimate from isotropic fractionation86 is the atomic number of radon, a radioactive noble gas that can accumulate in buildings from underlying rock and soil.
DocumentedScience
Geography
+86 reaches China, the largest telephone network in the world by connections. It sits in the East Asian 8x block, and like most countries with very large networks its domestic numbers run longer than the international average.
DocumentedGeographyGeography: China
Culture
The American slang verb 'to 86' something or someone — meaning to discard, cancel, or refuse service to — is documented in US diner and bar culture from the 1930s, though its exact origin is disputed.
DisputedCultureGeography: United States
Common questions
What does it mean to 86 something?
To get rid of it — a kitchen and bar term for an item that has run out, or a customer who is barred. It is documented in American diner slang from the 1930s. Several origin stories circulate (a menu code, a New York address, a soup-kitchen capacity) and none is well evidenced; the usage is far better attested than any explanation of it.
Is 86 a prime number?
No, 86 is not prime.
What are the factors of 86?
The factors of 86 are 1, 2, 43, 86.
What is 86 in Roman numerals?
86 in Roman numerals is LXXXVI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 5 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026