1970
1970 is year zero for Unix time.
- Even
- Composite
Where 1970 fits
Why 1970 is special
Computers count seconds from midnight on 1 January 1970, a choice made for convenience when Unix was being written and now embedded in most of the world's software. Dates before it are negative numbers, which is why some systems refuse birthdays earlier than 1970.
Same number, different meanings
How 1970 is understood across different contexts — never implying one meaning because of another.
- Mathematics
Computers count seconds from midnight on 1 January 1970, a choice made for convenience when Unix was being written and now embedded in most of the world's software. Dates before it are negative numbers, which is why some systems refuse birthdays earlier than 1970.
- History
In 1970, the first Earth Day was held, and Apollo 13 returned safely after an explosion.
- Technology & computing
Computers count time in seconds from 1 January 1970, a choice of convenience when Unix was written and now embedded almost everywhere. Earlier dates are negative numbers, which is why some systems still reject birthdays before 1970 rather than handling them.
1970 is part of
Factors & digit properties
- Divisors (8)
- 1, 2, 5, 10, 197, 394, 985, 1970
- Prime factorisation
- 2 × 5 × 197
- Digit sum
- 17
- Digital root
- 8
Representations
- Decimal
- 1970
- Scientific notation
- 1.970 × 10^3
Roman numerals
M C M L X X
MCMLXX uses the subtractive pair CM: a hundred before a thousand — a thousand minus a hundred.
Binary
1 1 1 1 0 1 1 0 0 1 0
1 × 1,024 + 1 × 512 + 1 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 0 × 1 = 1,970
Octal
3 6 6 2
3 × 512 + 6 × 64 + 6 × 8 + 2 × 1 = 1,970
Hexadecimal
7 b 2
7 × 256 + b × 16 + 2 × 1 = 1,970
Read as powers of two: 1,024 + 512 + 256 + 128 + 32 + 16 + 2 = 1,970.
In historical numeral systems
Egyptian
1 lotus, 9 coils of rope, 7 hobbles
1 × 1,000 + 9 × 100 + 7 × 10 = 1,970. 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), 5 corner wedges (units place)
32 × 60 + 50 = 1970. 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
ARPANET's first message was sent in 1969 and the Unix epoch begins the following year, bracketing the start of two systems still in use.
View 1969 →A signed 32-bit count of seconds from the start of 1970 runs out in January 2038, so one number sets the other.
View 2038 →History
In 1970, the first Earth Day was held, and Apollo 13 returned safely after an explosion.
DocumentedHistoryGeography: globalPeriod: 1970The Unix epoch was set at the start of 1970 as a convenient recent date when the system was written, not for any external significance. A 32-bit signed count of seconds from it reaches only to 2038, which is the direct cause of that deadline.
DocumentedHistoryGeography: GlobalPeriod: 1970–
Technology & computing
Computers count time in seconds from 1 January 1970, a choice of convenience when Unix was written and now embedded almost everywhere. Earlier dates are negative numbers, which is why some systems still reject birthdays before 1970 rather than handling them.
DocumentedTechnology & computing
Common questions
Is 1970 a prime number?
No, 1970 is not prime.
What are the factors of 1970?
The factors of 1970 are 1, 2, 5, 10, 197, 394, 985, 1970.
What is 1970 in Roman numerals?
1970 in Roman numerals is MCMLXX. CM is subtractive: a hundred before a thousand — a thousand minus a hundred. Written additively it would be MDCCCCLXX, 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: 3 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026