30
30 is the atomic number of zinc and the length of four calendar months (April, June, September, November).
- Even
- Composite
Where 30 fits
Why 30 is special
30 sits at the short end of the calendar's month-length split — 30 or 31 days, with February the sole exception.
Same number, different meanings
How 30 is understood across different contexts — never implying one meaning because of another.
- Mathematics
30 sits at the short end of the calendar's month-length split — 30 or 31 days, with February the sole exception.
- Science
30 is the atomic number of zinc.
- Everyday life
April, June, September and November each have 30 days — the shortest of the standard (non-February) calendar months.
Factors & digit properties
- Divisors (8)
- 1, 2, 3, 5, 6, 10, 15, 30
- Prime factorisation
- 2 × 3 × 5
- Digit sum
- 3
- Digital root
- 3
Representations
- Decimal
- 30
- Binary
- 11110
- Octal
- 36
- Hexadecimal
- 1e
- Roman numeral
- XXX
- Scientific notation
- 3.000 × 10^1
Other mathematical patterns
- Abundant number
- Harshad (Niven) number
Related numbers & connections
15 is a factor of 30 (15 × 2 = 30).
View 15 →Mathematically related
- has factor15
why?
Strength 0.50, confidence "high".
Science
30 is the atomic number of zinc.
DocumentedScience
Everyday life
April, June, September and November each have 30 days — the shortest of the standard (non-February) calendar months.
DocumentedEveryday life
Common questions
Is 30 a prime number?
No, 30 is not prime.
What are the factors of 30?
The factors of 30 are 1, 2, 3, 5, 6, 10, 15, 30.
What is 30 in Roman numerals?
30 in Roman numerals is XXX.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026