Beer can pyramid
A beer can pyramid, often called a beeramid (a portmanteau of "beer" and "pyramid"), is a pyramid made from discarded beer cans. Beer can pyramids are built as empty beer cans became available, slowly growing as the night (or week or month) wears on. In most cases, though, it is a temporary structure, eventually giving way to the inevitable clean-up or accidental destruction. The impermanence of the structure lends itself to easily removing it from wherever it has grown; combined with the great ease of creating a structure of relatively impressive size, beer can pyramids remain  popular today, especially when one considers it is often easier to contribute an empty beer can to the beeramid than it is to deposit the can in the appropriate recycling receptacle. A beer can pyramid was shown on the outside of Duff Gardens in "The Simpsons" episode 9F11 "Selma's Choice", in 1993. The pyramid is a pointed parody of Cinderella's Castle at Walt Disney World. While Bart is awed to be standing in the presence of the real thing, Lisa points out that "twenty-two immigrant laborers died in its construction." On 23 September 2000, the Malaysian Can  team, consisting of 12 college students from the INTI College Subang Jaya, Malaysia built a free standing can pyramid created from 9,455 empty aluminium drink cans in 24 minutes at the Mid Valley Megamall in Kuala Lumpur, Malaysia. It had a square base of 30 × 30 cans, measuring 1.98 m  × 1.98 m (6 ft 6 in × 6 ft 6 in). This feat made a successful entry into the Guinness World Record and to-date this record has yet to be broken. Another attempt to break the world record Beer Can Pyramid was made with beer cans over  5 metres high and contained 10,660 cans. It was built by the Melbourne University Student Union in 2005, and was featured on "Blokesworld" and in mX. Mathematics. For beer can pyramid of height "N" layers, if the base is a square then the number of cans is expressed by the sum: formula_1 The solution is the square pyramidal number. If the base is a triangle then the number of cans is expressed by the sum: formula_2 The solution is the tetrahedral number.