Q: How is 640 written in Roman Numerals?
A: DCXL
Roman Numerals are an ancient way of writing numbers that originated in ancient Rome.
It is still used today, but mainly for date purposes (like with Super Bowl L for Super Bowl 50) or for movie series (Star Wars IV - A New Hope).
Here are the main symbols that are used:
| 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
| I | V | X | L | C | D | M |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| I | II | III | IV | V | VI | VII | VIII | IX |
| 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 |
| X | XX | XXX | XL | L | LX | LXX | LXXX | XC |
| 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 |
| C | CC | CCC | CD | D | DC | DCC | DCCC | CM |
For numbers over 1,000, you put a dash over the top of the Roman Numeral to indicate multiplied by 1,000.
| 5,000 | 10,000 | 50,000 | 100,000 | 500,000 | 1,000,000 |
| V | X | L | C | D | M |
To convert 640 to Roman Numerals we need to split it up into place values (ones, tens, hundreds, etc.), like this:
| Place Value | Number | Roman Numeral |
|---|---|---|
| Hundreds | 600 | DC |
| Tens | 40 | XL |
Please note, we skipped place values that equal 0.
You then combine them all together (starting from the top) to get DCXL.