What does CMXVIII mean?

CMXVIII is the Roman numeral for 918 — 900 + 10 + 5 + 1 + 1 + 1.

How do you write 918 in Roman numerals?

Take the largest value that fits and repeat until nothing is left: CM (900), then X (10), then V (5), then I (1), then I (1), then I (1). That gives CMXVIII.

918 in Roman numerals

CMXVIII

Number (1–3,999 for numerals)

Roman numeral

918 is written CMXVIII in Roman numerals. That is 6 symbol groups added together, reading left to right from the largest value down.

How it breaks down

CMXVIII = 900 + 10 + 5 + 1 + 1 + 1 = 918
Group	Value	Subtraction	Running total
CM	900	M − C	900
X	10	—	910
V	5	—	915
I	1	—	916
I	1	—	917
I	1	—	918

Why the smaller symbol comes first

CMXVIII uses subtractive notation in one place: CM means M minus C, or 900. 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	yes — 1×
X	10	yes — 1×
L	50	no
C	100	yes — 1×
D	500	no
M	1,000	yes — 1×

The same number, other ways

In words: Nine hundred eighteen
Roman numeral: CMXVIII
Symbol count: 7 characters
Binary: 1110010110
Hexadecimal: 396

The numbers either side

Number	Roman numeral
916	CMXVI
917	CMXVII
918	CMXVIII ←
919	CMXIX
920	CMXX

Common questions

What is 918 in Roman numerals?: 918 is CMXVIII.
What does CMXVIII mean?: CMXVIII is the Roman numeral for 918 — 900 + 10 + 5 + 1 + 1 + 1.
How do you write 918 in Roman numerals?: Take the largest value that fits and repeat until nothing is left: CM (900), then X (10), then V (5), then I (1), then I (1), then I (1). That gives CMXVIII.

Sources

Calculated on this page — At One Place

How these figures are compiled and checked