9 in Roman Numerals
9
I (subtracted)X
nine
How IX is formed
| Place | Value | Symbols |
|---|---|---|
| Units | 9 | I (subtracted)X |
| Total | 9 | IX |
IX is a subtractive pair: I written before X means 10 − 1 = 9.
The same pair closes every number that ends in 9: XIX, XXIX, XCIX.
Common mistakes
Wrong: VIIII
Why isn't 9 written as VIIII?
A symbol can't be repeated four times in a row. 9 is IX (10 − 1), not VIIII.
Where you'll see IX
Super Bowl IX was played on January 12, 1975 at Tulane Stadium in New Orleans: the Pittsburgh Steelers beat the Minnesota Vikings 16–6.
Some documents write the month in Roman numerals so it isn't confused with the day: IX is September.
The Games of the IX Olympiad were held in Amsterdam in 1928.
Using IX
As the day of a date, 9 is IX: December 9 is XII.IX written month.day, or IX.XII written day.month. Convert a full date
Numbers near 9
Properties of 9
- Prime factors
- 3²
- Divisors
- 1, 3, 9
- Even or odd
- Odd
- Prime number
- No
- Letters in IX
- 2
9 is a perfect square: 3 × 3.
9,000 in Roman numerals
With a bar over it (vinculum), I̅X̅ means 9 × 1,000 = 9,000. How Roman numerals work