What does CDXXV mean?

CDXXV is the Roman numeral for 425 — 400 + 10 + 10 + 5.

How do you write 425 in Roman numerals?

Take the largest value that fits and repeat until nothing is left: CD (400), then X (10), then X (10), then V (5). That gives CDXXV.

425 in Roman numerals

CDXXV

Number (1–3,999 for numerals)

Roman numeral

425 is written CDXXV in Roman numerals. That is 4 symbol groups added together, reading left to right from the largest value down.

How it breaks down

CDXXV = 400 + 10 + 10 + 5 = 425
Group	Value	Subtraction	Running total
CD	400	D − C	400
X	10	—	410
X	10	—	420
V	5	—	425

Why the smaller symbol comes first

CDXXV uses subtractive notation in one place: CD means D minus C, or 400. A smaller symbol placed before a larger one is subtracted from it rather than added, which is why IX is nine and not eleven.

Only six such pairs are valid — IV, IX, XL, XC, CD and CM. That restriction is what makes the notation unambiguous: IIII and IC both look like they should work, but neither is standard, and only one spelling of any number is correct.

The symbols

Symbol	Value	Used here
I	1	no
V	5	yes — 1×
X	10	yes — 2×
L	50	no
C	100	yes — 1×
D	500	yes — 1×
M	1,000	no

The same number, other ways

In words: Four hundred twenty-five
Roman numeral: CDXXV
Symbol count: 5 characters
Binary: 110101001
Hexadecimal: 1A9

The numbers either side

Number	Roman numeral
423	CDXXIII
424	CDXXIV
425	CDXXV ←
426	CDXXVI
427	CDXXVII

Common questions

What is 425 in Roman numerals?: 425 is CDXXV.
What does CDXXV mean?: CDXXV is the Roman numeral for 425 — 400 + 10 + 10 + 5.
How do you write 425 in Roman numerals?: Take the largest value that fits and repeat until nothing is left: CD (400), then X (10), then X (10), then V (5). That gives CDXXV.

Sources

Calculated on this page — At One Place

How these figures are compiled and checked