540
The interior angles of any pentagon add up to 540 degrees.
- Even
- Composite
Where 540 fits
Why 540 is special
The rule generalises: an n-sided polygon's interior angles total 180 times (n − 2), because any polygon can be cut into that many triangles. 540 is the pentagon's case, and it is why a regular pentagon's corners are 108 degrees rather than a round number.
Factors & digit properties
- Divisors (24)
- 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 27, 30, 36, 45, 54, 60, 90, 108, 135, 180, 270, 540
- Prime factorisation
- 2^2 × 3^3 × 5
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 540
- Scientific notation
- 5.400 × 10^2
Roman numerals
D X L
DXL uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 0 0 0 0 1 1 1 0 0
1 × 512 + 0 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 0 × 1 = 540
Octal
1 0 3 4
1 × 512 + 0 × 64 + 3 × 8 + 4 × 1 = 540
Hexadecimal
2 1 c
2 × 256 + 1 × 16 + c × 1 = 540
Read as powers of two: 512 + 16 + 8 + 4 = 540.
In historical numeral systems
Egyptian
5 coils of rope, 4 hobbles
5 × 100 + 4 × 10 = 540. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
9 vertical wedges (sixties place), empty units place
9 × 60 + 0 = 540. Places are separated by a space on the tablet, with the higher place written first. The second place is empty, and this is precisely the case the early system could not write unambiguously — the same wedges alone would also read as 1.
Greek (Ionic)
phi, then mu, marked as a numeral
phi-mu + keraia
phi + mu written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then qof, then mem
tav-qof-mem
tav (400) + qof (100) + mem (40) = 540, written in descending order.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Abundant number
- Harshad (Niven) number
Related numbers & connections
A pentagon's interior angles total 540 degrees because it divides into three triangles. The rule is 180 times two fewer than the number of sides, for any polygon.
View 180 →Mathematically related
- is a multiple of180
why?
Strength 0.50, confidence "high".
Mathematics
Any polygon's interior angles total 180 times two fewer than its number of sides, because it can be cut into that many triangles. For a pentagon that is 540, and dividing by five gives the 108-degree corner of the regular case.
DocumentedMathematics
Common questions
Is 540 a prime number?
No, 540 is not prime.
What are the factors of 540?
The factors of 540 are 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 27, 30, 36, 45, 54, 60, 90, 108, 135, 180, 270, 540.
What is 540 in Roman numerals?
540 in Roman numerals is DXL. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be DXXXX, which Roman inscriptions used freely — the strict subtractive form is a later convention.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026