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78 record

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

List of numbers — Integers << 70 71 72 73 74 75 76 77 78 79 >>
Cardinal	seventy-eight
Ordinal	78th (seventy-eighth)
Factorization	<math>2 \cdot 3 \cdot 13<math>
Divisors	2, 3, 6, 13, 26, 39
Roman numeral	LXXVIII
Binary	1001110
Hexadecimal	4E

In mathematics

78 is a triangular number, and its factorization makes it a sphenic number.

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

In other fields

78 is also:

• The atomic number of platinum.
• 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 22 cards of the major arcana (including the fool) and the 56 cards of the minor arcana make up 78 cards.
• 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.