909
The Roland TR-909 is the drum machine behind house and techno.
- Odd
- Composite
Where 909 fits
Why 909 is special
It replaced the 808's analogue sounds with samples for cymbals while keeping analogue drums, and its hi-hats and kick define the rhythmic vocabulary of dance music. It also sold badly when new.
Factors & digit properties
- Divisors (6)
- 1, 3, 9, 101, 303, 909
- Prime factorisation
- 3^2 × 101
- Digit sum
- 18
- Digital root
- 9
Representations
- Decimal
- 909
- Scientific notation
- 9.090 × 10^2
Roman numerals
C M I X
CMIX uses the subtractive pair IX: one before ten — ten minus one.
Binary
1 1 1 0 0 0 1 1 0 1
1 × 512 + 1 × 256 + 1 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 909
Octal
1 6 1 5
1 × 512 + 6 × 64 + 1 × 8 + 5 × 1 = 909
Hexadecimal
3 8 d
3 × 256 + 8 × 16 + d × 1 = 909
Read as powers of two: 512 + 256 + 128 + 8 + 4 + 1 = 909.
In historical numeral systems
Egyptian
9 coils of rope, 9 strokes
9 × 100 + 9 × 1 = 909. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge + 5 vertical wedges (sixties place), 9 vertical wedges (units place)
15 × 60 + 9 = 909. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sampi, then theta, marked as a numeral
sampi-theta + keraia
sampi + 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 tet
tav-tav-qof-tet
tav (400) + tav (400) + qof (100) + tet (9) = 909, 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
Related numbers & connections
The TR-909's step sequencer divides a bar into sixteen, tying its programming directly to the time signature in use.
The TB-303 and TR-909 were sold as accompaniment for solo musicians, failed commercially, and together produced acid house when used against their design intent.
View 303 →Media & popular culture
The TR-909 followed the 808 and also sold poorly, then became foundational to house and techno once units reached second-hand shops. The pattern repeated exactly.
DocumentedMedia & popular culturePeriod: 1983
Common questions
Is 909 a prime number?
No, 909 is not prime.
What are the factors of 909?
The factors of 909 are 1, 3, 9, 101, 303, 909.
What is 909 in Roman numerals?
909 in Roman numerals is CMIX. IX is subtractive: one before ten — ten minus one. Written additively it would be DCCCCVIIII, 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