129
ISO 129 governs dimensioning on technical drawings.
- Odd
- Composite
Where 129 fits
Why 129 is special
It fixes how a dimension is written and where tolerances go, which is what allows a drawing made in one country to be manufactured in another.
129 is part of
Factors & digit properties
- Divisors (4)
- 1, 3, 43, 129
- Prime factorisation
- 3 × 43
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 129
- Scientific notation
- 1.290 × 10^2
Roman numerals
C X X I X
CXXIX uses the subtractive pair IX: one before ten — ten minus one.
Binary
1 0 0 0 0 0 0 1
1 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 129
Octal
2 0 1
2 × 64 + 0 × 8 + 1 × 1 = 129
Hexadecimal
8 1
8 × 16 + 1 × 1 = 129
Read as powers of two: 128 + 1 = 129.
In historical numeral systems
Egyptian
1 coil of rope, 2 hobbles, 9 strokes
1 × 100 + 2 × 10 + 9 × 1 = 129. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 vertical wedges (sixties place), 9 vertical wedges (units place)
2 × 60 + 9 = 129. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
rho, then kappa, then theta, marked as a numeral
rho-kappa-theta + keraia
rho + kappa + theta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
qof, then kaf, then tet
qof-kaf-tet
qof (100) + kaf (20) + tet (9) = 129, written in descending order.
Maya
1 bar + 1 dot (upper, twenties place) over 1 bar + 4 dots (lower, units place)
6 × 20 + 9 = 129. 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
- Happy number
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
General drawing principles come first and dimensioning rules are applied within them.
View 128 →Other connections
- developed from128
why?
Strength 0.50, confidence "high".
Technology & computing
ISO 129 specifies the presentation of dimensions and tolerances on technical product documentation, including arrangement, arrowheads and indication rules.
DocumentedTechnology & computingGeography: International — ISO member bodiesPeriod: 1985–
Common questions
Is 129 a prime number?
No, 129 is not prime.
What are the factors of 129?
The factors of 129 are 1, 3, 43, 129.
What is 129 in Roman numerals?
129 in Roman numerals is CXXIX. IX is subtractive: one before ten — ten minus one. Written additively it would be CXXVIIII, 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