What does CCCXLIII mean?

CCCXLIII is the Roman numeral for 343 — 100 + 100 + 100 + 40 + 1 + 1 + 1.

How do you write 343 in Roman numerals?

Take the largest value that fits and repeat until nothing is left: C (100), then C (100), then C (100), then XL (40), then I (1), then I (1), then I (1). That gives CCCXLIII.

343 in Roman numerals

CCCXLIII

Number (1–3,999 for numerals)

Roman numeral

343 is written CCCXLIII in Roman numerals. That is 7 symbol groups added together, reading left to right from the largest value down.

How it breaks down

CCCXLIII = 100 + 100 + 100 + 40 + 1 + 1 + 1 = 343
Group	Value	Subtraction	Running total
C	100	—	100
C	100	—	200
C	100	—	300
XL	40	L − X	340
I	1	—	341
I	1	—	342
I	1	—	343

Why the smaller symbol comes first

CCCXLIII 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	yes — 3×
V	5	no
X	10	yes — 1×
L	50	yes — 1×
C	100	yes — 3×
D	500	no
M	1,000	no

The same number, other ways

In words: Three hundred forty-three
Roman numeral: CCCXLIII
Symbol count: 8 characters
Binary: 101010111
Hexadecimal: 157

The numbers either side

Number	Roman numeral
341	CCCXLI
342	CCCXLII
343	CCCXLIII ←
344	CCCXLIV
345	CCCXLV

Common questions

What is 343 in Roman numerals?: 343 is CCCXLIII.
What does CCCXLIII mean?: CCCXLIII is the Roman numeral for 343 — 100 + 100 + 100 + 40 + 1 + 1 + 1.
How do you write 343 in Roman numerals?: Take the largest value that fits and repeat until nothing is left: C (100), then C (100), then C (100), then XL (40), then I (1), then I (1), then I (1). That gives CCCXLIII.

Sources

Calculated on this page — At One Place

How these figures are compiled and checked