88
A standard piano has 88 keys, spanning just over seven octaves. 88 is also the atomic number of radium, which Marie Curie isolated in 1898.
- Even
- Composite
Where 88 fits
Why 88 is special
88 connects two very different domains: the radioactive element that helped launch nuclear science, and the 52-white/36-black key layout every modern piano shares.
Same number, different meanings
How 88 is understood across different contexts — never implying one meaning because of another.
- Mathematics
88 connects two very different domains: the radioactive element that helped launch nuclear science, and the 52-white/36-black key layout every modern piano shares.
- Technology & computing
Kerberos uses port 88 for ticket exchange. It underlies Windows domain authentication, which is why time synchronisation failures break logins: tickets carry timestamps with a narrow tolerance.
- Science
There are 88 constellations recognised by the International Astronomical Union (worldwide, since 1922).
- Culture
A modern piano has eighty-eight keys spanning just over seven octaves, a range settled by Steinway in the 1880s and adopted generally. Instruments with more keys exist and remain rare.
- Media & popular culture
A standard modern piano keyboard has 88 keys — 52 white and 36 black.
Factors & digit properties
- Divisors (8)
- 1, 2, 4, 8, 11, 22, 44, 88
- Prime factorisation
- 2^3 × 11
- Digit sum
- 16
- Digital root
- 7
Representations
- Decimal
- 88
- Scientific notation
- 8.800 × 10^1
Roman numerals
L X X X V I I I
Binary
1 0 1 1 0 0 0
1 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 0 × 1 = 88
Octal
1 3 0
1 × 64 + 3 × 8 + 0 × 1 = 88
Hexadecimal
5 8
5 × 16 + 8 × 1 = 88
Read as powers of two: 64 + 16 + 8 = 88.
In historical numeral systems
Egyptian
8 hobbles, 8 strokes
8 × 10 + 8 × 1 = 88. 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 + 8 vertical wedges (units place)
1 × 60 + 28 = 88. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
pi, then eta, marked as a numeral
pi-eta + keraia
pi + eta 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 het
pe-het
pe (80) + het (8) = 88, written in descending order.
Chinese numerals
bā shí bā
bā shí bā
八 before 十 multiplies it: 8 tens. 八 after it adds 8. The written form mirrors the arithmetic — "bā shí bā". The financial (anti-fraud) form is 捌拾捌.
Maya
4 dots (upper, twenties place) over 1 bar + 3 dots (lower, units place)
4 × 20 + 8 = 88. 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
- Palindromic number
- Abundant number
- Repdigit
Related numbers & connections
44 is a factor of 88 (44 × 2 = 88).
View 44 →88 appears in Numbers in space, the topic covering numbers that carry a documented astronomy fact.
88 is treated as especially auspicious in Chinese-speaking contexts because it doubles the character associated with prosperity.
Mathematically related
- has factor44
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inSpace and astronomy
why?
Strength 0.50, confidence "high".
- appears inRadio and communications
why?
Strength 0.50, confidence "high".
- appears inStandard piano keyboard
why?
Strength 0.50, confidence "high".
Culturally related
- is considered lucky inChinese-speaking contexts
why?
Strength 0.50, confidence "high".
Other connections
- is associated withIAU-recognised constellations
why?
Strength 0.50, confidence "high".
- is associated with12
why?
Strength 0.50, confidence "high".
Technology & computing
Kerberos uses port 88 for ticket exchange. It underlies Windows domain authentication, which is why time synchronisation failures break logins: tickets carry timestamps with a narrow tolerance.
DocumentedTechnology & computingGeography: International — IETFPeriod: 1993–The bottom of the FM broadcast band is 88 megahertz (ITU Regions 1 and 2; Japan differs).
DocumentedTechnology & computingGeography: ITU Regions 1 and 2; Japan differsKerberos on port 88 authenticates by issuing time-limited tickets rather than sending passwords to each service, which is what makes a single sign-on across a corporate network possible. Because tickets are time-stamped, a clock more than a few minutes out breaks authentication — one of the more confusing failure modes in enterprise IT.
DocumentedTechnology & computing
Science
There are 88 constellations recognised by the International Astronomical Union (worldwide, since 1922).
DocumentedScienceGeography: worldwide, since 1922There are 88 constellations the sky is divided into (worldwide, fixed by the IAU in 1922). The boundaries are exact lines of right ascension and declination, so every point in the sky belongs to precisely one — including the parts with no visible stars.
DocumentedScienceGeography: worldwide, fixed by the IAU in 1922Mercury's orbital period is 88 days (the Solar System). Its day is longer than two of its years in one sense and shorter in another: it rotates three times for every two orbits, so a solar day on Mercury lasts about 176 Earth days.
DocumentedScienceGeography: the Solar System88 is the atomic number of radium. Marie Curie isolated it in 1898, and its glow made it a commercial novelty in luminous paint before the fatal consequences for the women who applied that paint became clear.
DocumentedSciencePeriod: 1898
Culture
A modern piano has eighty-eight keys spanning just over seven octaves, a range settled by Steinway in the 1880s and adopted generally. Instruments with more keys exist and remain rare.
DocumentedCultureGeography: Widely adopted internationallyPeriod: 1880s–
Media & popular culture
A standard modern piano keyboard has 88 keys — 52 white and 36 black.
DocumentedMedia & popular culture
Common questions
Why does a piano have 88 keys?
Because Steinway settled on that range in the 1880s and the rest of the industry followed. Eighty-eight keys span just over seven octaves, from A0 to C8 — beyond which the strings are short and stiff enough that pitch becomes hard for the ear to place. Instruments with more keys exist; they have never displaced the standard.
Is 88 a prime number?
No, 88 is not prime.
What are the factors of 88?
The factors of 88 are 1, 2, 4, 8, 11, 22, 44, 88.
What is 88 in Roman numerals?
88 in Roman numerals is LXXXVIII.
Is 88 a lucky number?
88 is considered lucky in Chinese-speaking contexts — a documented cultural association, not a mathematical property.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 9 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026