342
IC 342 is the Hidden Galaxy.
- Even
- Composite
Where 342 fits
Why 342 is special
It would be among the brightest galaxies in the sky if it were not directly behind the plane of the Milky Way, where dust absorbs most of its light.
Factors & digit properties
- Divisors (12)
- 1, 2, 3, 6, 9, 18, 19, 38, 57, 114, 171, 342
- Prime factorisation
- 2 × 3^2 × 19
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 342
- Scientific notation
- 3.420 × 10^2
Roman numerals
C C C X L I I
CCCXLII uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 0 1 0 1 0 1 1 0
1 × 256 + 0 × 128 + 1 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 1 × 2 + 0 × 1 = 342
Octal
5 2 6
5 × 64 + 2 × 8 + 6 × 1 = 342
Hexadecimal
1 5 6
1 × 256 + 5 × 16 + 6 × 1 = 342
Read as powers of two: 256 + 64 + 16 + 4 + 2 = 342.
In historical numeral systems
Egyptian
3 coils of rope, 4 hobbles, 2 strokes
3 × 100 + 4 × 10 + 2 × 1 = 342. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
5 vertical wedges (sixties place), 4 corner wedges + 2 vertical wedges (units place)
5 × 60 + 42 = 342. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
tau, then mu, then beta, marked as a numeral
tau-mu-beta + keraia
tau + mu + beta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
shin, then mem, then bet
shin-mem-bet
shin (300) + mem (40) + bet (2) = 342, written in descending order.
Maya
3 bars + 2 dots (upper, twenties place) over 2 dots (lower, units place)
17 × 20 + 2 = 342. 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
- Abundant number
- Harshad (Niven) number
Related numbers & connections
Both are large spirals close to the galactic plane, where Milky Way dust dims what would otherwise be prominent.
View 6946 →Other connections
- is associated with6946
why?
Strength 0.50, confidence "high".
Science
IC 342 is a large spiral galaxy close to the galactic plane. Interstellar dust in the Milky Way substantially dims it, which is why it was not catalogued earlier.
DocumentedSciencePeriod: 1892–
Common questions
Is 342 a prime number?
No, 342 is not prime.
What are the factors of 342?
The factors of 342 are 1, 2, 3, 6, 9, 18, 19, 38, 57, 114, 171, 342.
What is 342 in Roman numerals?
342 in Roman numerals is CCCXLII. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be CCCXXXXII, 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