# 70 (number)

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

 ← 69 70 71 →
Cardinalseventy
Ordinal70th
(seventieth)
Factorization2 × 5 × 7
Divisors1, 2, 5, 7, 10, 14, 35, 70
Greek numeralΟ´
Roman numeralLXX
Binary10001102
Ternary21213
Senary1546
Octal1068
Duodecimal5A12
Hebrewע
Lao

## In mathematics

70 is:

The sum of the first 24 squares starting from 1 is 702 = 4900, i.e. a square pyramidal number. This is the only non trivial solution to the cannonball problem and relates 70 to the Leech lattice and thus string theory.

## Number name

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; other French-speaking regions such as Belgium, Switzerland, Aosta Valley and Jersey use septante.[8])

## Notes

1. ^ "Sloane's A007304 : Sphenic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
2. ^ "Sloane's A000326 : Pentagonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
3. ^ "Sloane's A051865 : 13-gonal (or tridecagonal) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
4. ^ "Sloane's A000332 : Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
5. ^ "Sloane's A006037 : Weird numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
6. ^ "Sloane's A059756 : Erdős-Woods numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
7. ^ The Official Highway Code, pub. Department for Transport (Revised 2007 Edition). ISBN 978-0-11-552814-9. A white circular sign with a black diagonal stripe indicates that the national speed limit applies. This depends on the vehicle type and grade of road. The table on p. 40 shows the highest speed permitted to be 70 mph, for normally-laden cars and motorcycles on dual-carriageways and motorways.
8. ^ 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".