243
+243 is the international calling code for Democratic Republic of the Congo.
- Odd
- Composite
Where 243 fits
Why 243 is special
The DRC is the second-largest country in Africa and holds most of the world's cobalt, which makes its mining sector central to battery supply chains far from it.
Same number, different meanings
How 243 is understood across different contexts — never implying one meaning because of another.
- Mathematics
The DRC is the second-largest country in Africa and holds most of the world's cobalt, which makes its mining sector central to battery supply chains far from it.
- Technology & computing
The military aviation emergency frequency is 243 megahertz (worldwide, ICAO and NATO). Exactly twice the civil distress frequency of 121.5 megahertz, so a transmitter's second harmonic reaches the other service. The pairing is deliberate rather than a coincidence of allocation.
- Geography
+243 reaches the Democratic Republic of the Congo, which supplies the majority of the world's cobalt. Battery production anywhere depends on a mineral concentrated almost entirely in one country.
243 is part of
Factors & digit properties
- Divisors (6)
- 1, 3, 9, 27, 81, 243
- Prime factorisation
- 3^5
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 243
- Scientific notation
- 2.430 × 10^2
Roman numerals
C C X L I I I
CCXLIII uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 1 1 1 0 0 1 1
1 × 128 + 1 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 243
Octal
3 6 3
3 × 64 + 6 × 8 + 3 × 1 = 243
Hexadecimal
f 3
f × 16 + 3 × 1 = 243
Read as powers of two: 128 + 64 + 32 + 16 + 2 + 1 = 243.
In historical numeral systems
Egyptian
2 coils of rope, 4 hobbles, 3 strokes
2 × 100 + 4 × 10 + 3 × 1 = 243. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
4 vertical wedges (sixties place), 3 vertical wedges (units place)
4 × 60 + 3 = 243. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sigma, then mu, then gamma, marked as a numeral
sigma-mu-gamma + keraia
sigma + mu + gamma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
resh, then mem, then gimel
resh-mem-gimel
resh (200) + mem (40) + gimel (3) = 243, written in descending order.
Maya
2 bars + 2 dots (upper, twenties place) over 3 dots (lower, units place)
12 × 20 + 3 = 243. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
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
- Deficient number
- Powerful number
- Harshad (Niven) number
Related numbers & connections
The Democratic Republic of the Congo and Angola share a long border, and both are dominated economically by minerals — cobalt and oil respectively.
View 244 →243 appears in Numbers in radio and communications, the topic covering numbers that carry a documented radio or communications fact.
Technology & computing
The military aviation emergency frequency is 243 megahertz (worldwide, ICAO and NATO). Exactly twice the civil distress frequency of 121.5 megahertz, so a transmitter's second harmonic reaches the other service. The pairing is deliberate rather than a coincidence of allocation.
DocumentedTechnology & computingGeography: worldwide, ICAO and NATO
Geography
+243 reaches the Democratic Republic of the Congo, which supplies the majority of the world's cobalt. Battery production anywhere depends on a mineral concentrated almost entirely in one country.
DocumentedGeographyGeography: Democratic Republic of the Congo
Common questions
Is 243 a prime number?
No, 243 is not prime.
What are the factors of 243?
The factors of 243 are 1, 3, 9, 27, 81, 243.
What is 243 in Roman numerals?
243 in Roman numerals is CCXLIII. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be CCXXXXIII, 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: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026