Billion

A billion is a word we use for a very large number. There are two ways people can mean this word, depending on where they live or what language they speak.

In most places today, especially in the United States and increasingly in Britain, a billion means 1,000,000,000. This is one thousand million, or ten to the ninth power. This way of counting is called the short scale.

In the past, and still in many other European languages, a billion meant 1,000,000,000,000. This is one million million, or ten to the twelfth power. This way of counting is called the long scale.

The change from the long scale to the short scale happened over time. Britain officially switched to the short scale in 1974, though it had been used more and more in technical writing and news since the 1950s. Even famous leaders like Winston Churchill talked about a billion meaning one thousand millions for practical financial reasons. Some countries still use the long scale meaning, and the word milliard can be used to mean one thousand million in these places.

History

The word billion began in the 16th century. It came from the word million and the prefix bi-, meaning “two.” At first, it meant a very large number: one million million (1,000,000² = 10¹²). This was called the “long scale.”

Later, French mathematicians changed the meaning. They used the “short scale,” where billion means one thousand million (10⁹). This new way of counting became common in the United States in the 19th century.

For a long time, Britain kept the old meaning. But in 1974, the British government decided to use the short scale meaning of billion. Now, billion commonly means one thousand million in all English-speaking countries.