1955
1955 is the year the polio vaccine was declared safe and effective.
- Odd
- Composite
Where 1955 fits
Why 1955 is special
Salk declined to patent it, and asked who would patent the sun. Polio cases in the United States fell by roughly 90 percent within five years, and the disease is now close to eradicated worldwide.
Same number, different meanings
How 1955 is understood across different contexts — never implying one meaning because of another.
- Mathematics
Salk declined to patent it, and asked who would patent the sun. Polio cases in the United States fell by roughly 90 percent within five years, and the disease is now close to eradicated worldwide.
- Technology & computing
In 1955, the polio vaccine was declared safe and effective (North America).
- Science
The Salk vaccine was declared safe and effective in 1955 and was not patented — Salk asked who would patent the sun. US polio cases fell roughly 90 percent within five years and the disease is now close to global eradication.
1955 is part of
Factors & digit properties
- Divisors (8)
- 1, 5, 17, 23, 85, 115, 391, 1955
- Prime factorisation
- 5 × 17 × 23
- Digit sum
- 20
- Digital root
- 2
Representations
- Decimal
- 1955
- Scientific notation
- 1.955 × 10^3
Roman numerals
M C M L V
MCMLV uses the subtractive pair CM: a hundred before a thousand — a thousand minus a hundred.
Binary
1 1 1 1 0 1 0 0 0 1 1
1 × 1,024 + 1 × 512 + 1 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 1,955
Octal
3 6 4 3
3 × 512 + 6 × 64 + 4 × 8 + 3 × 1 = 1,955
Hexadecimal
7 a 3
7 × 256 + a × 16 + 3 × 1 = 1,955
Read as powers of two: 1,024 + 512 + 256 + 128 + 32 + 2 + 1 = 1,955.
In historical numeral systems
Egyptian
1 lotus, 9 coils of rope, 5 hobbles, 5 strokes
1 × 1,000 + 9 × 100 + 5 × 10 + 5 × 1 = 1,955. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
3 corner wedges + 2 vertical wedges (sixties place), 3 corner wedges + 5 vertical wedges (units place)
32 × 60 + 35 = 1955. 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
Related numbers & connections
1955 is a year in the 20th century, in the 1950s.
Insulin's discoverers sold the patent for a dollar in 1921 and Salk declined to patent the polio vaccine in 1955. Both decisions are cited in every modern argument about drug pricing.
View 1921 →Technology & computing
In 1955, the polio vaccine was declared safe and effective (North America).
DocumentedTechnology & computingGeography: North AmericaPeriod: 1955
Science
The Salk vaccine was declared safe and effective in 1955 and was not patented — Salk asked who would patent the sun. US polio cases fell roughly 90 percent within five years and the disease is now close to global eradication.
DocumentedSciencePeriod: 1955
Common questions
Is 1955 a prime number?
No, 1955 is not prime.
What are the factors of 1955?
The factors of 1955 are 1, 5, 17, 23, 85, 115, 391, 1955.
What is 1955 in Roman numerals?
1955 in Roman numerals is MCMLV. CM is subtractive: a hundred before a thousand — a thousand minus a hundred. Written additively it would be MDCCCCLV, 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: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026