155
155 is the highest possible break in snooker.
- Odd
- Composite
Where 155 fits
Why 155 is special
The maximum is normally 147, but a free ball after a foul adds an extra colour as a red, allowing 155. It has never been made in professional competition — the highest official break remains 147, which is itself rare enough to be newsworthy.
Factors & digit properties
- Divisors (4)
- 1, 5, 31, 155
- Prime factorisation
- 5 × 31
- Digit sum
- 11
- Digital root
- 2
Representations
- Decimal
- 155
- Scientific notation
- 1.550 × 10^2
Roman numerals
C L V
Binary
1 0 0 1 1 0 1 1
1 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 155
Octal
2 3 3
2 × 64 + 3 × 8 + 3 × 1 = 155
Hexadecimal
9 b
9 × 16 + b × 1 = 155
Read as powers of two: 128 + 16 + 8 + 2 + 1 = 155.
In historical numeral systems
Egyptian
1 coil of rope, 5 hobbles, 5 strokes
1 × 100 + 5 × 10 + 5 × 1 = 155. 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), 3 corner wedges + 5 vertical wedges (units place)
2 × 60 + 35 = 155. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
rho, then nu, then epsilon, marked as a numeral
rho-nu-epsilon + keraia
rho + nu + epsilon 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 nun, then he
qof-nun-he
qof (100) + nun (50) + he (5) = 155, written in descending order.
Maya
1 bar + 2 dots (upper, twenties place) over 3 bars (lower, units place)
7 × 20 + 15 = 155. 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
- Semiprime
Related numbers & connections
Snooker's normal maximum is 147; a free ball after a foul raises the theoretical maximum to 155. No professional has ever made one in competition.
View 147 →Other connections
- contrasts with147
why?
Strength 0.50, confidence "high".
Sport
A free ball after a foul lets a colour be potted as a red, raising snooker's theoretical maximum from 147 to 155. No professional has ever made one in competition, and the 147 itself is uncommon enough to be reported as news when it happens.
DocumentedSportA 155 break requires a free ball at the start of the frame, effectively adding an extra red and black to the maximum. It has never been recorded in professional competition.
DocumentedSportGeography: International
Common questions
Is 155 a prime number?
No, 155 is not prime.
What are the factors of 155?
The factors of 155 are 1, 5, 31, 155.
What is 155 in Roman numerals?
155 in Roman numerals is CLV.
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