70

## In mathematics

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

**70** is:

* a sphenic number because it factors as 3 distinct primes.
* a Pell number.
* the seventh pentagonal number.
* the fourth tridecagonal number.
* the fifth pentatope number.
* the number of ways to choose 4 objects out of 8 if order does not matter. This makes it a central binomial coefficient.
* the smallest weird number, a natural number that is abundant but not semiperfect.
* a palindromic number in bases 9 (779), 13 (5513) and 34 (2234).
* a Harshad number in bases 6, 8, 9, 10, 11, 13, 14, 15 and 16.
* an Erdős–Woods number, since it is possible to find sequences of **70** consecutive integers such that each inner member shares a factor with either the first or the last member.

The sum of the first 24 squares starting from 1 is **70**2. This relates **70** to the Leech lattice and thus string theory.

## In science

* **70** is the atomic number of ytterbium, a lanthanide

## In religion

* In Jewish tradition:
	+ Seventy souls went down to Egypt to begin the Hebrews' Egyptian exile (Genesis 46:27).
	+ There is a core of **70** nations and **70** world languages, paralleling the **70** names in the Table of Nations.
	+ There were **70** men in the Great Sanhedrin, the Supreme Court of ancient Israel. (Sanhedrin 1:4.)
	+ According to the Jewish Aggada, there are **70** perspectives ("faces") to the Torah (Numbers Rabbah 13:15).
	+ Seventy elders were assembled by Moses on God's command in the desert (Numbers 11:16–30).
	+ Psalm 90:10 allots three score and ten (**70** years) for a man's life, and the Mishnah attributes that age to "strength" (Avot 5:32), as one who survives that age is described by the verse as "the strong".
	+ 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 Christianity:
	+ In Matthew 18:21–22, Jesus tells Peter to forgive people seventy times seven times.
	+ In Luke 10:1–24, Jesus appoints Seventy Disciples and sends them out in pairs to preach the Gospel.
* Seventy is a priesthood office in the Latter Day Saint religion.
* 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 the Prophet Muhammad's adversaries during the Battle of Badr.
	+ **70** of the Prophet Muhammad's followers are martyred at the Battle of Uhud.
	+ In Shia Islam, there are **70** martyrs among Imam Hussein's followers during the tragedy of Karbala.

## In law

* In certain cases, copyrights expire after **70** years.

## In sports

* In Olympic archery, the targets are **70** meters from the archers.
* In college football, two teams scored **70** points in bowl games, the most in such contests: first the West Virginia Mountaineers against the Clemson Tigers in the 2012 Orange Bowl, and the Army Black Knights against the Houston Cougars in the 2018 Armed Forces Bowl.
* The number of the laps of the Canadian Grand Prix and Hungarian Grand Prix.

## In other fields

* **70** miles per hour is a common speed limit for freeways in many American states, primarily in the central United States (in the Eastern U.S. the speed limit is generally 65, in the Western U.S. it is 75).
* **70** miles per hour is the national speed limit in the United Kingdom for cars and motorcycles on the best grades of road.
* **70** years of marriage is marked by a platinum wedding anniversary.
* **70** is the hull number of the U.S. Navy's nuclear aircraft carrier USS *Carl Vinson* (CVN-70), named after U.S. Representative Carl Vinson.
* The French department Haute-Saône is number **70**.
* As a year, "**70**" may refer to **70** BC, AD **70**, or 1970.
* The number **70** is frequently referenced by the musical duo Boards of Canada: they have songs titled "Sixtyten" (*Music Has the Right to Children*, 1998) and "The Smallest Weird Number" (*Geogaddi*, 2002), and their record label is named Music**70**.
* In the Far Eastern culture of China, Japan, Korea, etc., **70** years old is called the Rare Age of the Olden Times (古稀 Guxi in Chinese, 古稀 Koki in Japanese, 고희 Gohui in Korean, etc.), as written in one of Du Fu's poems.[*citation needed*]
* 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

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