49 (number)
Template:Refimprove Template:Infobox number 49 (forty-nine) is the natural number following 48 and preceding 50.
In mathematics
49 is the square of the prime number seven. It appears in the Padovan sequence.[1]
Along with the number that immediately derives from it, 77, 49 is the only number under 100 whose home prime is unknown (Template:As of).Template:Citation needed 49 is the smallest discriminant of a totally real cubic field.[2]
Reciprocal
The fraction Template:Sfrac is a repeating decimal with a period of 42:
- Template:Sfrac = Template:Overline (42 digits repeat)
There are 42 positive integers less than 49 and coprime to 49. (42 is the period.) Multiplying 020408163265306122448979591836734693877551 by each of these integers results in a cyclic permutation of the original number.
The repeating number can be obtained from 02 and repetition of doubles placed at two places to the right because Template:Frac satisfies:
In other fields
During the Manhattan Project, plutonium was also often referred to simply as "49". Number 4 was for the last digit in 94 (atomic number of plutonium) and 9 for the last digit in Pu-239, the weapon-grade fissile isotope used in nuclear bombs.[3][4]
49er, one who participated in the 1849 California Gold Rush. This meaning has endured and things continue to be referred to as "49er," such as a member of the San Francisco 49ers team of the National Football League.
A 49 is a party after a powwow or any gathering of American Indians, held by the participants. It is also type of song that is sung on such occasions. A 49 is typically held in an isolated place and features drumming and singing.[5]