979
979 is the second ISBN prefix, allocated because 978 was running out.
- Odd
- Composite
Where 979 fits
Why 979 is special
Its introduction means the ten-digit form cannot represent every ISBN, so systems that still assume ten digits are silently unable to handle newer books.
979 is part of
Factors & digit properties
- Divisors (4)
- 1, 11, 89, 979
- Prime factorisation
- 11 × 89
- Digit sum
- 25
- Digital root
- 7
Representations
- Decimal
- 979
- Scientific notation
- 9.790 × 10^2
Roman numerals
C M L X X I X
CMLXXIX uses the subtractive pair IX: one before ten — ten minus one.
Binary
1 1 1 1 0 1 0 0 1 1
1 × 512 + 1 × 256 + 1 × 128 + 1 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 979
Octal
1 7 2 3
1 × 512 + 7 × 64 + 2 × 8 + 3 × 1 = 979
Hexadecimal
3 d 3
3 × 256 + d × 16 + 3 × 1 = 979
Read as powers of two: 512 + 256 + 128 + 64 + 16 + 2 + 1 = 979.
In historical numeral systems
Egyptian
9 coils of rope, 7 hobbles, 9 strokes
9 × 100 + 7 × 10 + 9 × 1 = 979. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge + 6 vertical wedges (sixties place), 1 corner wedge + 9 vertical wedges (units place)
16 × 60 + 19 = 979. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sampi, then omicron, then theta, marked as a numeral
sampi-omicron-theta + keraia
sampi + omicron + theta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then tav, then qof, then ayin, then tet
tav-tav-qof-ayin-tet
tav (400) + tav (400) + qof (100) + ayin (70) + tet (9) = 979, written in descending order.
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
- Palindromic number
- Deficient number
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
978 and 979 are the two ISBN prefixes. Books issued under 979 have no ten-digit form at all, which quietly breaks systems that still assume one.
View 978 →Other connections
- is associated with978
why?
Strength 0.50, confidence "high".
Technology & computing
Books issued under 979 have no ten-digit equivalent. Any system still storing ISBNs in ten characters cannot represent them, which is a quiet and ongoing data problem in library and retail software.
DocumentedTechnology & computing
Common questions
Is 979 a prime number?
No, 979 is not prime.
What are the factors of 979?
The factors of 979 are 1, 11, 89, 979.
What is 979 in Roman numerals?
979 in Roman numerals is CMLXXIX. IX is subtractive: one before ten — ten minus one. Written additively it would be DCCCCLXXVIIII, 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: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026