242 (number)

← 241 242 243 →
← 240 241 242 243 244 245 246 247 248 249 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred forty-two
Ordinal	242nd (two hundred forty-second)
Factorization	2 × 112
Greek numeral	ΣΜΒ´
Roman numeral	CCXLII, ccxlii
Binary	111100102
Ternary	222223
Senary	10426
Octal	3628
Duodecimal	18212
Hexadecimal	F216

242 (two hundred [and] forty-two) is the natural number following 241 and preceding 243.

242 is the smallest integer to start a run of four consecutive integers with the same number of divisors. ^{[1] [2]}

242 is a nontotient ^[3] since there is no integer with 242 coprimes below it.

242 is a palindrome. ^[4]

242 is the number of parallelogram polyominoes with 8 cells. ^[5]

242 is the difference between 355 and 113, two numbers used in an approximation of pi,

${\displaystyle {\frac {355}{113}}=3.14159292035\ldots }$

(This fraction is slightly larger than ${\displaystyle \pi }$, by a factor of around ${\displaystyle 0.000000266764\dots }$)

242 is the sum of elements in a 5-orthoplex: 32 polychora, 80 cells, 80 faces, 40 edges, and 10 vertices.

References

1. R. K. Guy Unsolved Problems in Number Theory, section B18.
2. D. Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Books, NY, 1986: 147, 176.
3. Sloane, N. J. A. (ed.). "SequenceA005277(nontotients)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
4. Sloane, N. J. A. (ed.). "SequenceA002113(palindromes in base 10)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
5. Sloane, N. J. A. (ed.). "SequenceA006958(Number of parallelogram polyominoes with n cells (also called staircase polyominoes, although that term is overused))". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.