30 (number)

30 (thirty) is the natural number following 29 and preceding 31.

In mathematics

30 is the sum of the first four squares, which makes it a square pyramidal number.

It is a primorial and is the smallest Giuga number.

30 is the smallest sphenic number, and the smallest of the form 2 × 3 × r, where r is a prime greater than 3. 30 has an aliquot sum of 42; the second sphenic number and all sphenic numbers of this form have an aliquot sum 12 greater than themselves. The aliquot sequence of 30 is 16 members long, it comprises (30,42,54,66,78,90,144,259,45,33,15,9,4,3,1,0)

Thirty has but one number for which it is the aliquot sum: the square number 841.

Adding up some subsets of its divisors (e.g., 5, 10 and 15) gives 30, hence 30 is a semiperfect number.

30 is the largest number such that all coprimes smaller than itself, except for 1, are prime.

A polygon with thirty sides is called a triacontagon.

The icosahedron and the dodecahedron are Platonic solids with 30 edges. The icosidodecahedron is an Archimedean solid with 30 vertices, and the Tutte–Coxeter graph is a symmetric graph with 30 vertices.

Michael Jackson

Michael Joseph Jackson (August 29, 1958 – June 25, 2009) was an American singer, songwriter, record producer, dancer, and actor. Called the King of Pop, his contributions to music and dance, along with his publicized personal life, made him a global figure in popular culture for over four decades.

The eighth child of the Jackson family, he debuted on the professional music scene along with his elder brothers Jackie, Tito, Jermaine, and Marlon as a member of the Jackson 5 in 1964, and began his solo career in 1971. In the early 1980s, Jackson became a dominant figure in popular music. The music videos for his songs, including those of "Beat It", "Billie Jean", and "Thriller" from his 1982 album Thriller, were credited with breaking down racial barriers and with transforming the medium into an art form and promotional tool. The popularity of these videos helped to bring the then-relatively-new television channel MTV to fame. His 1987 album Bad spawned the U.S. Billboard Hot 100 number-one singles "I Just Can't Stop Loving You", "Bad", "The Way You Make Me Feel", "Man in the Mirror", and "Dirty Diana", becoming the first album to have five number-one singles on the Billboard Hot 100. With videos such as "Black or White" and "Scream", he continued to innovate the medium throughout the 1990s, as well as forging a reputation as a touring solo artist. Through stage and video performances, Jackson popularized a number of complicated dance techniques, such as the robot and the moonwalk, to which he gave the name. His distinctive sound and style has influenced numerous artists of various music genres.