421 in Roman numerals

The number 421 is written in Roman numerals like this: CDXXI

CDXXI = 421

How to write 421 in Roman numerals

Split the number by place value and write each part in Roman numerals:

• 400 = CD (500 − 100)
• 20 = XX
• 1 = I

Put the parts together: CD + XX + I = CDXXI.

When a smaller symbol comes before a larger one, it is subtracted.

Going the other way? See the Roman numeral CDXXI.

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420 in Roman numerals: CDXX

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422 in Roman numerals: CDXXII

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