93
Earth orbits about 93 million miles from the Sun — the distance defined as one astronomical unit. 93 is also the atomic number of neptunium, the first element ever made heavier than uranium.
- Odd
- Composite
Where 93 fits
Why 93 is special
93's element opened an entirely new region of the periodic table in 1940 — every element heavier than uranium followed its lead.
93 connects to:
- 31 — has factor
- numbers in space — appears in
Same number, different meanings
How 93 is understood across different contexts — never implying one meaning because of another.
- Mathematics
93's element opened an entirely new region of the periodic table in 1940 — every element heavier than uranium followed its lead.
- History
Neptunium was made at Berkeley in 1940 by Edwin McMillan and Philip Abelson, bombarding uranium with neutrons — the first element heavier than uranium ever produced, and the discovery that showed the periodic table did not simply stop at 92. It was named for Neptune, the planet beyond Uranus, and plutonium followed the same logic months later. McMillan shared the 1951 Nobel Prize in Chemistry for the work.
- Everyday life
93 is the usual premium grade at American petrol stations. The figure is an octane rating — resistance to knocking, the premature ignition that damages an engine — and the number is not comparable internationally: the United States posts an average of two test methods, while Europe posts the higher of them, so US 93 corresponds to roughly 98 on a European pump. Higher octane is not better fuel; it is only better for an engine designed to need it.
- Science
The diameter of the observable universe is about 93 billion light-years (the observable universe). Larger than light could have travelled in the age of the universe, because space expanded while the light was in transit. This is comoving distance, which is the only one that makes the comparison meaningful.
93 is part of
Factors & digit properties
- Divisors (4)
- 1, 3, 31, 93
- Prime factorisation
- 3 × 31
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 93
- Scientific notation
- 9.300 × 10^1
Roman numerals
X C I I I
XCIII uses the subtractive pair XC: ten before a hundred — a hundred minus ten.
Binary
1 0 1 1 1 0 1
1 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 93
Octal
1 3 5
1 × 64 + 3 × 8 + 5 × 1 = 93
Hexadecimal
5 d
5 × 16 + d × 1 = 93
Read as powers of two: 64 + 16 + 8 + 4 + 1 = 93.
In historical numeral systems
Egyptian
9 hobbles, 3 strokes
9 × 10 + 3 × 1 = 93. 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), 3 corner wedges + 3 vertical wedges (units place)
1 × 60 + 33 = 93. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
koppa, then gamma, marked as a numeral
koppa-gamma + keraia
koppa + gamma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tsadi, then gimel
tsadi-gimel
tsadi (90) + gimel (3) = 93, written in descending order.
Chinese numerals
jiǔ shí sān
jiǔ shí sān
九 before 十 multiplies it: 9 tens. 三 after it adds 3. The written form mirrors the arithmetic — "jiǔ shí sān". The financial (anti-fraud) form is 玖拾參.
Maya
4 dots (upper, twenties place) over 2 bars + 3 dots (lower, units place)
4 × 20 + 13 = 93. 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
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
31 is a factor of 93 (31 × 3 = 93).
View 31 →93 appears in Numbers in space, the topic covering numbers that carry a documented astronomy fact.
Mathematically related
- has factor31
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inSpace and astronomy
why?
Strength 0.50, confidence "high".
History
Neptunium was made at Berkeley in 1940 by Edwin McMillan and Philip Abelson, bombarding uranium with neutrons — the first element heavier than uranium ever produced, and the discovery that showed the periodic table did not simply stop at 92. It was named for Neptune, the planet beyond Uranus, and plutonium followed the same logic months later. McMillan shared the 1951 Nobel Prize in Chemistry for the work.
DocumentedHistoryPeriod: 1940
Everyday life
93 is the usual premium grade at American petrol stations. The figure is an octane rating — resistance to knocking, the premature ignition that damages an engine — and the number is not comparable internationally: the United States posts an average of two test methods, while Europe posts the higher of them, so US 93 corresponds to roughly 98 on a European pump. Higher octane is not better fuel; it is only better for an engine designed to need it.
DocumentedEveryday lifeGeography: United States
Science
The diameter of the observable universe is about 93 billion light-years (the observable universe). Larger than light could have travelled in the age of the universe, because space expanded while the light was in transit. This is comoving distance, which is the only one that makes the comparison meaningful.
DocumentedScienceGeography: the observable universeEarth orbits at an average of about 93 million miles from the Sun — roughly 150 million kilometres — the distance defined as one astronomical unit. The figure is an average because the orbit is elliptical, varying by about three million miles across the year.
DocumentedScience93 is the atomic number of neptunium, the first transuranium (heavier-than-uranium) element ever synthesised.
DocumentedSciencePeriod: 1940
Mathematics
93 factors as 3 × 31, sitting directly between the prime 89 and the notable 100.
DocumentedMathematics
Common questions
How far is the Sun from Earth?
About 93 million miles, or 150 million kilometres — the distance defined as one astronomical unit. It is an average: the orbit is elliptical, so the real distance varies by roughly three million miles over the year.
Why is neptunium named after a planet?
Because uranium was named after Uranus, and neptunium is the next element up — so the next planet out gave the name. Plutonium, element 94, continued the sequence months later. Both were made at Berkeley in 1940–41, and neptunium was the first element heavier than uranium ever produced, which is how it became clear the periodic table did not simply stop at 92.
What does 93 octane mean?
Resistance to knocking — premature ignition that damages an engine — not energy content or quality. 93 is the usual American premium grade. The number is not comparable internationally: the US posts an average of two test methods while Europe posts the higher, so US 93 is roughly a European 98. Higher octane only helps an engine designed to need it.
Is 93 a prime number?
No, 93 is not prime.
What are the factors of 93?
The factors of 93 are 1, 3, 31, 93.
What is 93 in Roman numerals?
93 in Roman numerals is XCIII. XC is subtractive: ten before a hundred — a hundred minus ten. Written additively it would be LXXXXIII, which Roman inscriptions used freely — the strict subtractive form is a later convention.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 6 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026