Number
729 in Roman numerals
729 is written DCCXXIX
Type any other number or numeral below to convert it.
Above 3,999? Type the barred part in brackets, e.g. (IV)CC = 4,200.
How DCCXXIX is built
Roman numerals are written one decimal place at a time, largest first.
- DCChundreds · 7D (500) plus CC (200) makes 700.
- XXtens · 2X written 2 times: 2 × 10 = 20.
- IXones · 9I before X means 10 − 1 = 9. This saves writing VIIII.
700 + 20 + 9 = 729
The pair IX uses subtraction: a smaller letter before a larger one is taken away from it. Only six pairs work this way: IV, IX, XL, XC, CD and CM. More on subtraction
Mistakes to avoid
- Not DCCXXVIIII (10 letters). That adds everything up without subtraction. The Romans sometimes wrote numbers this way, and clocks still show 4 as IIII, but today DCCXXIX (7 letters) is the standard.
About the number 729
- 729 is odd and can be split into prime factors: 3 × 3 × 3 × 3 × 3 × 3, or in Roman numerals III × III × III × III × III × III.
- 729 is a square number: 27 × 27 (XXVII × XXVII).
- 729 is a cube number: 9 × 9 × 9.
- DCCXXIX has 7 letters. 216 of the numbers up to 1,000 have longer numerals.
Counting from 721 to 730
Every number from 721 to 730 starts DCCXX (720); only the ending changes.
| Number | Roman numeral |
|---|---|
| 721 | DCCXXI |
| 722 | DCCXXII |
| 723 | DCCXXIII |
| 724 | DCCXXIV |
| 725 | DCCXXV |
| 726 | DCCXXVI |
| 727 | DCCXXVII |
| 728 | DCCXXVIII |
| 729 | DCCXXIX |
| 730 | DCCXXX |