Step by step
- Before a larger numeral: subtract (IV = 4, IX = 9).
- After a larger numeral: add (VI = 6, XI = 11).
- For standard writing, use IV; IIII is acceptable on clocks.
At a glance
| Numeral | Rule | Value |
|---|---|---|
| IV | 5 − 1 | 4 |
| VI | 5 + 1 | 6 |
| IX | 10 − 1 | 9 |
Related questions
Is IIII wrong?
It is not standard today, but it is historically correct and traditional on clocks.
Why do clocks use IIII?
Explanations include visual balance with VIII and tradition; there is no single proven reason.
Is IIX valid for 8?
No, only one smaller numeral can be subtracted: 8 is VIII.
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Updated November 14, 2026.