35
35mm is the film gauge that defined cinema for a century, and 35 is the minimum age the US Constitution sets for the presidency. It is also the fifth tetrahedral number, and the atomic number of bromine.
- Odd
- Composite
Where 35 fits
Why 35 is special
35mm's dominance in both movie projection and still photography makes 35 one of the more recognisable numbers in visual media, despite an unremarkable mathematical profile (5 × 7).
35 connects to:
- 70 — is a factor of
- film gauge — appears in
Same number, different meanings
How 35 is understood across different contexts — never implying one meaning because of another.
- Mathematics
35mm's dominance in both movie projection and still photography makes 35 one of the more recognisable numbers in visual media, despite an unremarkable mathematical profile (5 × 7).
- Technology & computing
35mm is the most common film gauge in cinema history, used for both theatrical projection and, informally, still photography.
- Law & regulation
Article II of the United States Constitution sets 35 as the minimum age for the presidency, alongside natural-born citizenship and fourteen years' residency. The threshold has never been amended, and the youngest person actually elected, John F. Kennedy, was 43.
- Science
35 is the atomic number of bromine, one of only two elements that are liquid at room temperature. Its compounds were once the basis of photographic film and later of flame retardants, several of which are now restricted.
35 is part of
Factors & digit properties
- Divisors (4)
- 1, 5, 7, 35
- Prime factorisation
- 5 × 7
- Digit sum
- 8
- Digital root
- 8
Representations
- Decimal
- 35
- Scientific notation
- 3.500 × 10^1
Roman numerals
X X X V
Binary
1 0 0 0 1 1
1 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 35
Octal
4 3
4 × 8 + 3 × 1 = 35
Hexadecimal
2 3
2 × 16 + 3 × 1 = 35
Read as powers of two: 32 + 2 + 1 = 35.
In historical numeral systems
Egyptian
3 hobbles, 5 strokes
3 × 10 + 5 × 1 = 35. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
3 corner wedges + 5 vertical wedges
35 fits in a single sexagesimal place: 3 corner wedges + 5 vertical wedges.
Greek (Ionic)
lambda, then epsilon, marked as a numeral
lambda-epsilon + keraia
lambda + epsilon written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
lamed, then he
lamed-he
lamed (30) + he (5) = 35, written in descending order.
Chinese numerals
sān shí wǔ
sān shí wǔ
三 before 十 multiplies it: 3 tens. 五 after it adds 5. The written form mirrors the arithmetic — "sān shí wǔ". The financial (anti-fraud) form is 參拾伍.
Maya
1 dot (upper, twenties place) over 3 bars (lower, units place)
1 × 20 + 15 = 35. 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
- Pentagonal number
- Semiprime
Related numbers & connections
35 is a factor of 70 (35 × 2 = 70).
View 70 →35mm is the most common film gauge in cinema history — the theatrical standard for over a century, against which the smaller 8mm and 16mm gauges are defined.
Mathematically related
- is a factor of70
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inFilm gauge
why?
Strength 0.50, confidence "high".
Technology & computing
35mm is the most common film gauge in cinema history, used for both theatrical projection and, informally, still photography.
DocumentedTechnology & computing
Law & regulation
Article II of the United States Constitution sets 35 as the minimum age for the presidency, alongside natural-born citizenship and fourteen years' residency. The threshold has never been amended, and the youngest person actually elected, John F. Kennedy, was 43.
DocumentedLaw & regulationGeography: United StatesPeriod: 1787-
Mathematics
35 is the fifth tetrahedral number: stack triangular layers of 1, 3, 6, 10 and 15 and the pile totals 35. It is the three-dimensional counterpart of the triangular numbers, and the reason a pyramid of stacked spheres reaches these particular totals.
DocumentedMathematics
Science
35 is the atomic number of bromine, one of only two elements that are liquid at room temperature. Its compounds were once the basis of photographic film and later of flame retardants, several of which are now restricted.
DocumentedScience
Common questions
Why is 35 the minimum age for a US president?
Article II of the Constitution sets it, alongside natural-born citizenship and fourteen years' residence. The Convention did not record much debate about the figure — the Senate's minimum is 30 and the House's 25, so the pattern is seniority by chamber rather than a calculated threshold. Several presidents have been elected in their forties; only Theodore Roosevelt took office younger, at 42.
What is a tetrahedral number?
The count of balls in a triangular pyramid. Stack triangular layers of 1, 3, 6, 10 and 15 and the pile totals 35 — the fifth tetrahedral number. It is the three-dimensional counterpart of the triangular numbers, which is why 35 keeps appearing in stacking and packing problems.
Is 35 a prime number?
No, 35 is not prime.
What are the factors of 35?
The factors of 35 are 1, 5, 7, 35.
What is 35 in Roman numerals?
35 in Roman numerals is XXXV.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 4 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026