0

Zero, written as 0, is a special number that means nothing or an empty amount. When you add zero to any number, the number stays the same. For example, adding zero to 5 still gives you 5. But if you multiply any number by zero, the answer is always zero.

Zero is very important in math because it helps us write numbers in a system called decimal notation. In this system, each position of a number stands for a different power of ten. Zero tells us that a certain power of ten has no value. For instance, in the number 205, the zero means there are no tens.

The idea of using zero as a number started a long time ago in India. It was later shared with the rest of the world by mathematicians from Islamic countries and became widely used in Europe thanks to a famous mathematician named Fibonacci. Different cultures, like the Maya people, also used zero on their own. There are many ways people say zero, such as "nought," "nil," or even "zilch" in casual talk.

Etymology

Main articles: Names for the number 0 and Names for the number 0 in English

The word zero came into English from the French word zéro. The French got it from the Italian word zero. This Italian word came from an older Arabic word, ṣifr, meaning "empty". The idea of zero as a number started in India and was shared with Europe by the Italian mathematician Fibonacci.

We use different words for zero in different situations. In everyday speech, we might say "nothing" or "none". In British English, people sometimes say "nought" or "naught". When saying numbers aloud, like in phone numbers or years, we often say "oh", as in "two oh one" for the area code 201. Some informal words for zero are "zip", "zilch", or "nada". In sports, scores of zero have special names, like "love" in tennis and "duck" in cricket.

History

Ancient Near East

Ancient Egyptian numbers were based on groups of ten. They used special symbols for counting, and in some old records, a special mark showed when nothing was added or taken away. This mark might have been one of the first ways people thought about the idea of zero.

Around the same time, people in Babylon used a system with groups of sixty. They left spaces to show missing numbers, but these spaces weren’t really numbers themselves.

Pre-Columbian Americas

In parts of Mexico and Central America, people used a calendar system that needed a symbol for zero. They used different shapes to show this, like a flower-like sign. This shows that even far away from Europe, people thought about zero.

Classical antiquity

The Greeks didn’t really use zero as a number. They sometimes used a letter to show when there were no numbers, but they didn’t think of it as a real number.

Later, a Greek scientist named Ptolemy used a special sign for zero when he studied the stars and the moon. This was one of the first times zero was used like a real number in science.

China

Chinese mathematicians used spaces to show zero when they did math with rods. Later, they started using a round symbol to show zero, but they still didn’t think of it as a real number.

India

In India, people used the word “śūnya” to mean empty or void, which is like zero. They also started using a place where nothing was, like a blank spot, to help with counting.

Middle Ages

Transmission to Islamic culture

Later, people in the Middle East learned about numbers from India and started using a special circle to show zero. This helped them do better math.

Transmission to Europe

From the Middle East, the idea of zero and new number symbols spread to Europe. A man named Fibonacci helped teach these numbers to people in Europe, making it easier for everyone to do math.

Symbols and representations

Main article: Symbols for zero

Today, we write the number 0 as a circle or oval shape. In the past, some printed letters looked like the number 0. Old typewriters sometimes mixed up the letter O and the number 0.

To avoid this, some systems use a special slashed zero ( 0 / ), especially in computers. Some screens put a dot in the middle of the zero. Different fonts help us tell the letter O and the number 0 apart.

Mathematics

See also: Null (mathematics)

Zero is an important number in math. It can stand for a missing digit in numbers. For example, in the number 205, the zero shows that there are no tens.

Zero is also a number on its own. Adding zero to any number does not change that number — for example, 5 plus zero is still 5. But multiplying any number by zero always gives zero. Dividing by zero does not work and is called undefined. Zero is special because it is neither positive nor negative, and it is the smallest whole number.

Physics

Zero is very important in physics. For some measurements, like absolute temperature in kelvins, zero is the smallest possible value. This is different from the Celsius scale, where zero was chosen to match the freezing point of water. When measuring sound, zero is set at the quietest sound people can hear, using units like decibels or phons. In physics, even when something seems empty, it can have a small amount of energy called zero-point energy. This is the least energy a system can have, according to quantum mechanical rules.

Computer science

Computers store information using binary code, which only uses two symbols: "0" and "1". These symbols show whether electricity is on or off in a wire. Programmers use languages easier for people to understand, but computers follow binary instructions directly.

In programming, zero is important. For example, in some languages, zero stands for "false" in true-or-false statements. When organizing lists of items, many modern languages start counting from zero. This helps programmers keep track of items, but it can sometimes cause confusion. For example, a list with ten items will have positions from zero to nine.

Zero also marks the end of text in certain programming situations and can show that a system operation was successful. Some computer systems have special ways to show zero, which can help avoid mistakes.

Other fields

In the study of animals and how they think, some scientists have found that some animals understand the idea of zero. This shows that thinking about numbers may have started early in many species.

Dating systems

Main article: Year zero

In some ways of counting years, the year 1 BC comes right before AD 1, and there is no year zero. But, in a special system used by scientists who study stars and planets, the year 1 BC is called year 0. The year 2 BC is called year −1, and so on.