78 (number)

From Wikipedia, the free encyclopedia

78 (seventy-eight) is the natural number following 77 and followed by 79.

<< 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	78 seventy-eight
Ordinal	78th seventy-eighth
Factorization	$2 \cdot 3 \cdot 13$
Divisors	1, 2, 3, 6, 13, 26, 39, 78
Roman numeral	LXXVIII
Binary	1001110
Hexadecimal	4E

1 In mathematics
2 In science
3 In other fields
4 References

[edit] In mathematics

78 is a triangular number, and its factorization makes it a sphenic number. As a multiple of perfect number, 78 is itself a semiperfect number.

77 and 78 form a Ruth-Aaron pair under the second definition in which repeated prime factors are counted as often as they occur.

Karl A. Dahlke proved in 1989 that 78 heptominos of this shape ( ), at a minimum, are required to fill a rectangle.

[edit] In science

The atomic number of platinum

In astronomy,

Messier object M78, a magnitude 8.0 diffuse nebula in the constellation Orion

The New General Catalogue object NGC 78, a magnitude 12.8 barred spiral galaxy in the constellation Pisces

The Saros number of the solar eclipse series which began on -463 June 9 and ended on 817 July 18. The duration of Saros series 78 was 1280.1 years, and it contained 72 solar eclipses.

The Saros number of the lunar eclipse series which began on -125 April 10 and ended on 1155 May 18. The duration of Saros series 78 was 1280.1 years, and it contained 72 lunar eclipses.

[edit] In other fields

78 is also:

The designation of Interstate 78, a freeway that runs from Pennsylvania to New York.
In reference to gramophone records, 78 refers those meant to be spun at 78 revolutions per minute. Compare: LP, 33 and 45.
A standard Tarot deck containing the 21 trump cards, the fool) and the 56 suit cards make up 78 cards.
The number of the French département Yvelines
The total number of gifts in the song The Twelve Days of Christmas (since 78 is the 12th triangular number).
The year AD 78, 78 BC, or 1978.
The number of lines that make up Metatron's Cube.