1803
1803 is the year of the Louisiana Purchase.
- Odd
- Composite
Where 1803 fits
Why 1803 is special
The United States doubled in size for about four cents an acre. France sold because the Haitian revolution had destroyed its plan for an American empire, so the purchase is a direct consequence of a successful slave revolt.
Same number, different meanings
How 1803 is understood across different contexts — never implying one meaning because of another.
- Mathematics
The United States doubled in size for about four cents an acre. France sold because the Haitian revolution had destroyed its plan for an American empire, so the purchase is a direct consequence of a successful slave revolt.
- History
Napoleon sold Louisiana because losing Saint-Domingue had removed the point of holding it. The United States doubled its territory at a price set by a French strategic collapse that a revolution of enslaved people had caused.
- Science
In 1803, John Dalton proposed that each element is made of identical atoms of a characteristic weight, giving chemistry its atomic theory (England).
1803 is part of
Factors & digit properties
- Divisors (4)
- 1, 3, 601, 1803
- Prime factorisation
- 3 × 601
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 1803
- Scientific notation
- 1.803 × 10^3
Roman numerals
M D C C C I I I
Binary
1 1 1 0 0 0 0 1 0 1 1
1 × 1,024 + 1 × 512 + 1 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 1,803
Octal
3 4 1 3
3 × 512 + 4 × 64 + 1 × 8 + 3 × 1 = 1,803
Hexadecimal
7 0 b
7 × 256 + 0 × 16 + b × 1 = 1,803
Read as powers of two: 1,024 + 512 + 256 + 8 + 2 + 1 = 1,803.
In historical numeral systems
Egyptian
1 lotus, 8 coils of rope, 3 strokes
1 × 1,000 + 8 × 100 + 3 × 1 = 1,803. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
3 corner wedges (sixties place), 3 vertical wedges (units place)
30 × 60 + 3 = 1803. Places are separated by a space on the tablet, with the higher place written first.
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
Related numbers & connections
1803 is a year in the 19th century, in the 1800s.
Napoleon sold Louisiana in 1803 because the Haitian revolution had destroyed the colonial plan it was meant to supply. Haiti's independence followed in 1804.
View 1804 →Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
Other connections
- developed from1804
why?
Strength 0.50, confidence "high".
History
Napoleon sold Louisiana because losing Saint-Domingue had removed the point of holding it. The United States doubled its territory at a price set by a French strategic collapse that a revolution of enslaved people had caused.
DocumentedHistoryGeography: United States and FrancePeriod: 1803In 1803, the Louisiana Purchase doubled the territory of the United States (North America).
DocumentedHistoryGeography: North AmericaPeriod: 1803
Science
In 1803, John Dalton proposed that each element is made of identical atoms of a characteristic weight, giving chemistry its atomic theory (England).
DocumentedScienceGeography: EnglandPeriod: 1803
Common questions
Is 1803 a prime number?
No, 1803 is not prime.
What are the factors of 1803?
The factors of 1803 are 1, 3, 601, 1803.
What is 1803 in Roman numerals?
1803 in Roman numerals is MDCCCIII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 3 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026