In many countries the public telephone network has a single emergency telephone number (sometimes known as the universal emergency telephone number or occasionally the emergency services number) that allows a caller to contact local emergency services for assistance. The emergency number differs from country to country; it is typically a three-digit number so that it can be easily remembered and dialed quickly. Some countries have a different emergency number for each of the different emergency services; these often differ only by the last digit. In the European Union, '112' was introduced as a common emergency call number during the 1990s, and as the GSM standard it is now a well known emergency number across the globe alongside the North American '911' and the British '999'.

The emergency telephone number is a special case in the country's telephone number plan. In the past, calls to the emergency telephone number were often routed over special dedicated circuits. Though with the advent of electronic exchanges these calls are now often mixed with ordinary telephone traffic, they still may be able to access circuits that other traffic cannot. Often the system is set up so that once a call is made to an emergency telephone number, it must be answered. Should the caller abandon the call, the line may still be held until the emergency service answers and releases the call.

1,000,000,000 (one billion, short scale; one thousand million or milliard, long scale) is the natural number following 999,999,999 and preceding 1,000,000,001.

In scientific notation, it is written as 10⁹.

A billion traditionally equated to one million, million, (1,000,000,000,000) though the short scale (American English) billion of merely one thousand million (1,000,000,000) has been adopted in finance and increasingly in other fields. The unambiguous term thousand million has the same meaning in both scales.

In South Asian English, it is known as 100 crore or 1 arab.

The term milliard can also be used to refer to 1,000,000,000; this name very often appears in other languages.

This terminology is rarely used in English outside of British English. The SI prefix giga indicates 1,000,000,000 times the base unit.

See Orders of magnitude (numbers) for larger numbers; and long and short scales.

The facts below give a sense of how large 1,000,000,000 (10⁹) is in the context of time according to current scientific evidence:

The 1.1"/75 caliber gun was an American anti-aircraft weapon of World War II. The name means that it had a bore diameter of 1.1 inches (28 mm) and barrel length of 75 × 1.1 inches = 82.5 inches (2.1 m), using the "caliber" nomenclature common to large artillery pieces.

It was developed when the U.S. Navy Bureau of Ordnance (BuOrd) decided that the .50 caliber machine gun was not adequate for future AA duties:

During the early part of World War II, they were deployed on most U.S. Navy warships of destroyer and larger size.

Due to teething problems that were never rectified, the gun was very unpopular with its crews. It was replaced with the Bofors 40 mm gun whenever possible, but served until the end of the war on some ships.

The guns were sometimes referred to as "Chicago Pianos."

Viswanathan Anand (Tamil: விசுவநாதன் ஆனந்த், IPA: [ʋiʃʋəˈn̪aːt̪ən ˈaːnən̪d̪]; born 11 December 1969) is an Indian chess Grandmaster and the current World Chess Champion. Anand has won the World Chess Championship five times (2000, 2007, 2008, 2010, 2012), and has been the undisputed World Champion since 2007. Anand became India's first grandmaster in 1988. He was also the first recipient of the Rajiv Gandhi Khel Ratna Award in 1991–92, India's highest sporting honor. In 2007, he was awarded India's second highest civilian award, the Padma Vibhushan, making him the first sportsperson to receive the award in Indian history.

He held the FIDE World Chess Championship from 2000 to 2002, at a time when the world title was split. He became the undisputed World Champion in 2007 and defended his title against Vladimir Kramnik in 2008. He then successfully defended his title in the World Chess Championship 2010 against Veselin Topalov and in the World Chess Championship 2012 against Boris Gelfand. As the reigning champion, he will face the winner of the upcoming Candidates Tournament for the World Chess Championship 2013.

Sven Magnus Øen Carlsen (born 30 November 1990) is a Norwegian chess Grandmaster and chess prodigy who is currently the number-one ranked player in the world. In January 2010 he became the seventh player in history to be ranked number one in the world on the official FIDE rating list. His peak rating is 2835, the second highest in history, after Garry Kasparov.

On 26 April 2004 Carlsen became a Grandmaster at the age of &1000000000000001300000013 years, &10000000000000148000000148 days, making him the third-youngest Grandmaster in history. On 1 January 2010 the new FIDE rating list was published, and at the age of &1000000000000001900000019 years, &1000000000000003200000032 days, he became the youngest chess player in history to be ranked world number one, breaking the record previously held by Vladimir Kramnik. Carlsen was also the 2009 World blitz chess champion.

His performance at the September–October 2009 Nanjing Pearl Spring tournament has been described as one of the greatest in history and lifted him to an Elo rating of 2801, making him the fifth player to achieve a rating over 2800 – and aged 18 years 10 months at the time, by far the youngest to do so.