Texas Instruments Ti-84 Plus Ce Graphing Calculator, Black

84 may refer to:

• 84 (number)
• one of the years 84 BC, AD 84, 1984, AD 2084
• 84 Lumber, a building materials supply company
• Eighty Four, Pennsylvania, an unincorporated census-designated place in Washington County, Pennsylvania, United States
• Seksendört, a Turkish pop group whose name means 84
• 84 Klio, a minor planet part of the Asteroid belt

Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have often been used to describe opposites such as good and evil, the Dark Ages versus the Age of Enlightenment, and night versus day. Since the Middle Ages, black has been the symbolic color of solemnity and authority, and for this reason it is still commonly worn by judges and magistrates.

Black was one of the first colors used by artists in Neolithic cave paintings. It was used in ancient Egypt and Greece as the color of the underworld. In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches, and magic. In the 14th century, it was worn by royalty, clergy, judges, and government officials in much of Europe. It became the color worn by English romantic poets, businessmen and statesmen in the 19th century, and a high fashion color in the 20th century. According to surveys in Europe and North America, it is the color most commonly associated with mourning, the end, secrets, magic, force, violence, fear, evil, and elegance.

Black is the most common ink color used for printing books, newspapers and documents, as it provides the highest contrast with white paper and thus is the easiest color to read. Similarly, black text on a white screen is the most common format used on computer screens. As of September 2019, the darkest material is made by MIT engineers from vertically aligned carbon nanotubes.

An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics.

The first solid-state electronic calculator was created in the early 1960s. Pocket-sized devices became available in the 1970s, especially after the Intel 4004, the first microprocessor, was developed by Intel for the Japanese calculator company Busicom. Modern electronic calculators vary from cheap, give-away, credit-card-sized models to sturdy desktop models with built-in printers. They became popular in the mid-1970s as the incorporation of integrated circuits reduced their size and cost. By the end of that decade, prices had dropped to the point where a basic calculator was affordable to most and they became common in schools.

In addition to general purpose calculators, there are those designed for specific markets. For example, there are scientific calculators, which include trigonometric and statistical calculations. Some calculators even have the ability to do computer algebra. Graphing calculators can be used to graph functions defined on the real line, or higher-dimensional Euclidean space. As of 2016, basic calculators cost little, but scientific and graphing models tend to cost more.

Computer operating systems as far back as early Unix have included interactive calculator programs such as dc and hoc, and interactive BASIC could be used to do calculations on most 1970s and 1980s home computers. Calculator functions are included in most smartphones, tablets, and personal digital assistant (PDA) type devices. With the very wide availability of smartphones and the like, dedicated hardware calculators, while still widely used, are less common than they once were. In 1986, calculators still represented an estimated 41% of the world's general-purpose hardware capacity to compute information. By 2007, this had diminished to less than 0.05%.

Texas ( TEK-səss, locally also TEK-siz; Spanish: Texas or Tejas, pronounced [ˈtexas]) is the most populous state in the South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and has an international border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south and southwest. Texas has a coastline on the Gulf of Mexico to the southeast. Covering 268,596 square miles (695,660 km²), the state has over 31 million residents as of 2024, and it is the second-largest state by both area and population. Texas is nicknamed the Lone Star State for its former status as an independent republic, the Republic of Texas.

Spain was the first European country to claim and control Texas. Following a short-lived colony controlled by France, Mexico controlled the land until 1836 when Texas won its independence, becoming the Republic of Texas. In 1845, Texas joined the United States of America as the 28th state. The state's annexation set off a chain of events that led to the Mexican–American War in 1846. Following victory by the United States, Texas remained a slave state until the American Civil War, when it declared its secession from the Union in early 1861 before officially joining the Confederate States of America on March 2. After the Civil War and the restoration of its representation in the federal government, Texas entered a long period of economic stagnation.

Historically, five major industries shaped the Texas economy prior to World War II: cattle, bison, cotton, timber, and oil. Before and after the Civil War, the cattle industry—which Texas came to dominate—was a major economic driver and created the traditional image of the Texas cowboy. In the later 19th century, cotton and lumber grew to be major industries as the cattle industry became less lucrative. Ultimately, the discovery of major petroleum deposits (Spindletop in particular) initiated an economic boom that became the driving force behind the economy for much of the 20th century. Texas developed a diversified economy and high tech industry during the mid-20th century. As of 2024, it has the second-highest number (52) of Fortune 500 companies headquartered in the United States. With a growing base of industry, the state leads in many industries, including tourism, agriculture, petrochemicals, energy, computers and electronics, aerospace, and biomedical sciences. Texas has led the U.S. in state export revenue since 2002 and has the second-highest gross state product.

The Dallas–Fort Worth metroplex and Greater Houston areas are the nation's fourth and fifth-most populous urban regions respectively. Its capital city is Austin. Due to its size and geologic features such as the Balcones Fault, Texas contains diverse landscapes common to both the U.S. Southern and the Southwestern regions. Most population centers are in areas of former prairies, grasslands, forests, and the coastline. Traveling from east to west, terrain ranges from coastal swamps and piney woods, to rolling plains and rugged hills, to the desert and mountains of the Big Bend.