What does CMXCVIII mean?

CMXCVIII is the Roman numeral for 998 — 900 + 90 + 5 + 1 + 1 + 1.

How do you write 998 in Roman numerals?

Take the largest value that fits and repeat until nothing is left: CM (900), then XC (90), then V (5), then I (1), then I (1), then I (1). That gives CMXCVIII.

998 in Roman numerals

CMXCVIII

Number (1–3,999 for numerals)

Roman numeral

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

How it breaks down

CMXCVIII = 900 + 90 + 5 + 1 + 1 + 1 = 998
Group	Value	Subtraction	Running total
CM	900	M − C	900
XC	90	C − X	990
V	5	—	995
I	1	—	996
I	1	—	997
I	1	—	998

Why the smaller symbol comes first

CMXCVIII uses subtractive notation in 2 places: CM means M minus C, or 900; XC means C minus X, or 90. 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 — 2×
D	500	no
M	1,000	yes — 1×

The same number, other ways

In words: Nine hundred ninety-eight
Roman numeral: CMXCVIII
Symbol count: 8 characters
Binary: 1111100110
Hexadecimal: 3E6

The numbers either side

Number	Roman numeral
996	CMXCVI
997	CMXCVII
998	CMXCVIII ←
999	CMXCIX
1,000	M

Common questions

What is 998 in Roman numerals?: 998 is CMXCVIII.
What does CMXCVIII mean?: CMXCVIII is the Roman numeral for 998 — 900 + 90 + 5 + 1 + 1 + 1.
How do you write 998 in Roman numerals?: Take the largest value that fits and repeat until nothing is left: CM (900), then XC (90), then V (5), then I (1), then I (1), then I (1). That gives CMXCVIII.

Sources

Calculated on this page — At One Place

How these figures are compiled and checked