What is 31 in Roman numerals?

31 is written as XXXI in Roman numerals. It combines three tens represented by X each and a single unit represented by I. There is no subtraction form used, so the numerals simply add to a total of thirty-one.

How is XXXI formed using Roman numeral rules?

XXXI follows additive notation: X (10) repeated three times gives thirty, and I (1) adds one. Roman numerals place larger values before smaller ones, so writing three Xs then I correctly represents thirty-one without requiring subtractive rules.

Why is 31 written as XXXI rather than alternative forms?

Standard Roman practice writes 31 as XXXI because tens are expressed with X and units with I. Although nonstandard variants like IIII or XXXX appear historically on monuments or clocks, orthodox notation favors three Xs followed by I for clarity and consistency.

What is a step-by-step method to convert 31 to Roman numerals?

To convert 31, subtract the largest Roman value not exceeding 31: X (10) fits three times, recording XXX and leaving 1. Then use I for the remainder. Combine XXX and I to form XXXI, equaling thirty-one.

How do you convert XXXI back into Arabic numerals?

Reading XXXI, add values from left to right: X (10) plus X (10) plus X (10) equals thirty, then add I (1) to reach thirty-one. No subtraction occurs because each symbol is equal or smaller than the previous one.

Where might you commonly see XXXI used in modern contexts?

XXXI appears in historical inscriptions, regnal lists, and dated monuments to indicate the thirty-first year or person. It also commonly marks chapters, sporting events, and Super Bowls when applicable, following Roman numeral convention for formal numbering and styling.

What symbols make up XXXI and what are their values?

XXXI consists of three X symbols and one I. Each X equals ten, so three Xs total thirty, while I equals one. Combining these values yields thirty-one: 10 + 10 + 10 + 1 = 31, illustrating simple additive notation.

Romanumerals

31 in Roman Numerals

Updated at: 09/28/2025

31 in Roman Numerals is written as XXXI, combining XXX for thirty and I for one; this additive form reflects the Roman numeral system’s use of repeated symbols, origin in ancient Rome, and practical application on clocks, inscriptions, and numbering sequences to represent cardinal values simply and clearly across historical and modern contexts.

XXXI

30 in Roman Numerals 32 in Roman Numerals

How to Write 31 in Roman Numerals?

To write 31 as a Roman numeral: break the number into 30 + 1. Represent 30 as three tens: 10 + 10 + 10 = XXX. Represent 1 as I. Combine the parts: XXX + I = XXXI. Therefore, 31 in Roman numerals is written as XXXI. This method follows standard Roman numeral rules and notation.

Breakdown of 31

XXX
=
30
I
=
1

Together, they form

XXXI

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Examples of 31 in Roman Numerals

Prime Properties of 31 (XXXI)

Mathematical Primer: 31 (XXXI) is a prime number with no divisors besides 1 and itself; expressible as 2 to the 5th minus 1, a Mersenne prime, and appears in binary as 11111, useful for teaching.

31 BCE and the Rise of Octavian

Historical Context: In 31 BCE, the decisive Battle of Actium sealed Octavian’s rise; inscriptions from the era use Roman numerals like XXXI to mark years, legion numbers, or memorial dates on monuments and coins across the empire.

Why 31 Inspired Baskin-Robbins’ Slogan

Cultural Curiosity: The number 31 (XXXI) inspired Baskin-Robbins’ famous slogan promising 31 ice cream flavors, one for each day of the month; this branding became a global cultural icon linking numerals to everyday choices.

Engraving Dates: Using XXXI for the 31st

Practical Application: When engraving anniversaries, legal documents, or calendar plaques, convert the day '31' into Roman numerals as XXXI for a classical aesthetic; ensure correct notation and spacing to preserve historical authenticity and legibility.

Gallium: Atomic Number 31 and a Melting Metal

Fun Trivia: Atomic number 31 corresponds to gallium (Ga), a soft metal that can melt in your hand near 29.8°C; museums sometimes label exhibits with Roman numerals like XXXI to attract curious visitors.

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Roman Numerals Near 31

Number	Roman
29	XXIX
30	XXX
31	XXXI
32	XXXII
33	XXXIII

Frequently Asked Questions

30 in Roman Numerals 32 in Roman Numerals