50
The United States has had 50 states since 1959, and a fiftieth anniversary is a golden jubilee. 50 is also the atomic number of tin, the metal that alloys with copper to make bronze.
- Even
- Composite
Where 50 fits
Why 50 is special
50 marks a half-century in age and anniversaries, and — since 1959 — the complete count of US states.
Same number, different meanings
How 50 is understood across different contexts — never implying one meaning because of another.
- Mathematics
50 marks a half-century in age and anniversaries, and — since 1959 — the complete count of US states.
- Everyday life
Fifty percent is the reference point for a majority, a pass mark in many systems and the point at which a probability is even. Its use as a threshold is convention, and the choice is why marginal cases cluster around it.
- History
A fiftieth anniversary is marked as a golden jubilee across many traditions, and fifty years is a common statutory period for copyright terms, records release and jubilee observance. The interval is arbitrary but widely institutionalised.
- Technology & computing
The Channel Tunnel is 50 kilometres (England and France, since 1994). Thirty-eight of them are under the sea, which was the longest undersea section of any tunnel until 2016.
- Culture
The United States has had fifty states since 1959, and the flag was redesigned to match. The number is fixed by admission rather than by geography, and proposals to admit further states recur without succeeding.
- Geography
The United States is made up of 50 states, the last two — Alaska and Hawaii — admitted in 1959.
- Law & regulation
There are 50 states in the United States (United States). Fixed since 1959. The flag's stars have been rearranged 27 times as states joined; the stripes have stayed at thirteen since 1818.
- Science
50 is the atomic number of tin. Alloyed with copper it gives bronze, the metal that named an age; today most tin goes into solder and into the thin protective coating inside food cans.
50 is part of
Factors & digit properties
- Divisors (6)
- 1, 2, 5, 10, 25, 50
- Prime factorisation
- 2 × 5^2
- Digit sum
- 5
- Digital root
- 5
Representations
- Decimal
- 50
- Scientific notation
- 5.000 × 10^1
Roman numerals
L
Binary
1 1 0 0 1 0
1 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 0 × 1 = 50
Octal
6 2
6 × 8 + 2 × 1 = 50
Hexadecimal
3 2
3 × 16 + 2 × 1 = 50
Read as powers of two: 32 + 16 + 2 = 50.
In historical numeral systems
Egyptian
5 hobbles
5 × 10 = 50. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
5 corner wedges
50 fits in a single sexagesimal place: 5 corner wedges.
Greek (Ionic)
nu, marked as a numeral
nu + keraia
A single letter, nu, marked with a keraia to show it is a number rather than a word.
Hebrew numerals
nun
nun
Chinese numerals
wǔ shí
wǔ shí
五 before 十 multiplies it: 5 tens. The written form mirrors the arithmetic — "wǔ shí". The financial (anti-fraud) form is 伍拾.
Maya
2 dots (upper, twenties place) over 2 bars (lower, units place)
2 × 20 + 10 = 50. 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
- Harshad (Niven) number
Related numbers & connections
25 is a factor of 50 (25 × 2 = 50).
View 25 →50 appears in Numbers in radio and communications, the topic covering numbers that carry a documented radio or communications fact.
Fifty percent is the reference point for a majority, which is why marginal cases cluster immediately either side of it.
View 51 →Mathematically related
- has factor25
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inRadio and communications
why?
Strength 0.50, confidence "high".
- appears inLaw and public systems
why?
Strength 0.50, confidence "high".
- appears inTransport
why?
Strength 0.50, confidence "high".
- appears inUS states
why?
Strength 0.50, confidence "high".
Everyday life
Fifty percent is the reference point for a majority, a pass mark in many systems and the point at which a probability is even. Its use as a threshold is convention, and the choice is why marginal cases cluster around it.
DocumentedEveryday lifeGeography: GlobalPeriod: long-standing
History
A fiftieth anniversary is marked as a golden jubilee across many traditions, and fifty years is a common statutory period for copyright terms, records release and jubilee observance. The interval is arbitrary but widely institutionalised.
DocumentedHistoryGeography: Widely observed internationallyPeriod: long-standing
Technology & computing
The Channel Tunnel is 50 kilometres (England and France, since 1994). Thirty-eight of them are under the sea, which was the longest undersea section of any tunnel until 2016.
DocumentedTechnology & computingGeography: England and France, since 1994The mains frequency is 50 hertz (most of the world outside the Americas). The split with North America's 60 hertz is an artefact of which manufacturers electrified which countries rather than a technical judgement — AEG standardised on 50 in Europe, Westinghouse on 60 in the United States. Fifty is slightly more efficient for transmission and slightly worse for lighting flicker, and neither difference decided anything.
DocumentedTechnology & computingGeography: most of the world outside the AmericasThe design life assumed for an ordinary building is 50 years (worldwide, structural codes). A design life is an assumption about maintenance and use, not a prediction of collapse. Bridges are commonly designed for 100 or 120 years and many stand far longer.
DocumentedTechnology & computingGeography: worldwide, structural codes
Culture
The United States has had fifty states since 1959, and the flag was redesigned to match. The number is fixed by admission rather than by geography, and proposals to admit further states recur without succeeding.
DocumentedCultureGeography: United StatesPeriod: 1959–
Geography
The United States is made up of 50 states, the last two — Alaska and Hawaii — admitted in 1959.
DocumentedGeographyGeography: United StatesPeriod: 1959
Law & regulation
There are 50 states in the United States (United States). Fixed since 1959. The flag's stars have been rearranged 27 times as states joined; the stripes have stayed at thirteen since 1818.
DocumentedLaw & regulationGeography: United States
Science
50 is the atomic number of tin. Alloyed with copper it gives bronze, the metal that named an age; today most tin goes into solder and into the thin protective coating inside food cans.
DocumentedScience
Common questions
What is a golden anniversary?
Fifty years of marriage, in the Western anniversary-naming convention that also gives silver at 25 and diamond at 60 or 75 depending on the country. The gold and silver tiers are the oldest; most of the others were added much later, some by the jewellery trade.
Is 50 a prime number?
No, 50 is not prime.
What are the factors of 50?
The factors of 50 are 1, 2, 5, 10, 25, 50.
What is 50 in Roman numerals?
50 in Roman numerals is L.
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