409 in Roman numerals

409 in Roman numerals is CDIX.

Pick any whole number from 1 to 3,999.

409 = \text{CDIX}

How to work it out

1
Take the biggest Roman value that fits, write its letter, subtract it, and repeat.
2
Here: 400 (CD) + 9 (IX) = 409.
3
Joined together: CDIX. (Four of the same letter in a row is never used: 4 is IV, 9 is IX, 40 is XL, 90 is XC, 400 is CD, 900 is CM.)

Value	Letters
400	CD
9	IX

What is 409 in Roman numerals?

CDIX.

How do you read CDIX?

CDIX = 400 + 9 = 409.