70 (number)

Mathematics

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

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, ; , short for . (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.)

Notes

References

References

1. "Sloane's A059756 : Erdős-Woods numbers". OEIS Foundation.
2. {{Cite OEIS. A000984. Central binomial coefficients: binomial(2n,n) as (2n)!/(n!)^2.
3. "Sloane's A006037 : Weird numbers". OEIS Foundation.
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".