What does DCCCXL mean?

DCCCXL is the Roman numeral for 840 — 500 + 100 + 100 + 100 + 40.

How do you write 840 in Roman numerals?

Take the largest value that fits and repeat until nothing is left: D (500), then C (100), then C (100), then C (100), then XL (40). That gives DCCCXL.

840 in Roman numerals

DCCCXL

Number (1–3,999 for numerals)

Roman numeral

840 is written DCCCXL in Roman numerals. That is 5 symbol groups added together, reading left to right from the largest value down.

How it breaks down

DCCCXL = 500 + 100 + 100 + 100 + 40 = 840
Group	Value	Subtraction	Running total
D	500	—	500
C	100	—	600
C	100	—	700
C	100	—	800
XL	40	L − X	840

Why the smaller symbol comes first

DCCCXL uses subtractive notation in one place: XL means L minus X, or 40. 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	no
X	10	yes — 1×
L	50	yes — 1×
C	100	yes — 3×
D	500	yes — 1×
M	1,000	no

The same number, other ways

In words: Eight hundred forty
Roman numeral: DCCCXL
Symbol count: 6 characters
Binary: 1101001000
Hexadecimal: 348

The numbers either side

Number	Roman numeral
838	DCCCXXXVIII
839	DCCCXXXIX
840	DCCCXL ←
841	DCCCXLI
842	DCCCXLII

Common questions

What is 840 in Roman numerals?: 840 is DCCCXL.
What does DCCCXL mean?: DCCCXL is the Roman numeral for 840 — 500 + 100 + 100 + 100 + 40.
How do you write 840 in Roman numerals?: Take the largest value that fits and repeat until nothing is left: D (500), then C (100), then C (100), then C (100), then XL (40). That gives DCCCXL.

Sources

Calculated on this page — At One Place

How these figures are compiled and checked