70 (number)

← 69 70 71 →
← 70 71 72 73 74 75 76 77 78 79 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	seventy
Ordinal	70th (seventieth)
Factorization	2 x 5 x 7
Divisors	1, 2, 5, 7, 10, 14, 35, 70
Greek numeral	Ο´
Roman numeral	LXX, lxx
Binary	10001102
Ternary	21213
Senary	1546
Octal	1068
Duodecimal	5A12
Hexadecimal	4616
Hebrew	ע
Lao	໗
Armenian	Հ
Babylonian numeral	𒐕𒌋
Egyptian hieroglyph	𓎌

70 (seventy) is the natural number following 69 and preceding 71.

Mathematics

70 is a composite number an Erdős–Woods number ^[1] , a Pell number, a central binomial coefficient ^[2] , and a primitive abundant number. 70 is the smallest weird number, which is a natural number that is abundant but not semiperfect. ^[3]

70 is also part of the only nontrivial solution pair to the cannonball problem, along with 24.

In religion

• In Jewish tradition, Ptolemy II Philadelphus ordered 72 Jewish elders to translate the Torah into Greek; the result was the Septuagint (from the Latin for "seventy"). The Roman numeral seventy, LXX, is the scholarly symbol for the Septuagint.

• In Islamic history and in Islamic interpretation the number 70 or 72 is most often and generally hyperbole for an infinite amount:
  • There are 70 dead among Muhammad's adversaries during the Battle of Badr.
  • 70 of Muhammad's followers are martyred at the Battle of Uhud.
  • In Shia Islam, there are 70 martyrs among Imam Hussein's followers during the Battle of Karbala.

In other fields

• In some traditions, 70 years of marriage is marked by a platinum wedding anniversary.
• Under Social Security (United States), the age at which a person can receive the maximum retirement benefits (and may do so and continue working without reduction of benefits).

Number name

Main article: Numeral (linguistics)

Several languages, especially ones with vigesimal number systems, do not have a specific word for 70: for example, French : soixante-dix, lit.  'sixty-ten'; Danish : halvfjerds, short for halvfjerdsindstyve, 'three and a half score'. (For French, this is true only in France, Canada and Luxembourg; other French-speaking regions such as Belgium, Switzerland, Aosta Valley and Jersey use septante.) ^[4]

References

1. "Sloane's A059756 : Erdős-Woods numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
2. Sloane, N. J. A. (ed.). "SequenceA000984(Central binomial coefficients: binomial(2*n,n) as (2*n)!/(n!)^2.)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
3. "Sloane's A006037 : Weird numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
4. Peter Higgins, Number Story. London: Copernicus Books (2008): 19. "Belgian French speakers however grew tired of this and introduced the new names septante, octante, nonante etc. for these numbers".