521 in Roman numerals

521 in Roman numerals is DXXI.

Pick any whole number from 1 to 3,999.

521 = \text{DXXI}

How to work it out

1
Take the biggest Roman value that fits, write its letter, subtract it, and repeat.
2
Here: 500 (D) + 10 (X) + 10 (X) + 1 (I) = 521.
3
Joined together: DXXI. (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.)

What is 521 in Roman numerals?

DXXI.

How do you read DXXI?

DXXI = 500 + 10 + 10 + 1 = 521.