One, written 1, is the number before two and after zero. It is a single entity with a value of 1.

The number one is a natural number, an integer. One is the first counting number, and the only positive integer (1, 2, 3, 4…) that is neither a prime nor a composite number.

One is not to be confused with the digit one (1), which is often used in place of “one” as a placeholder in numeric contexts (e.g., “I have three apples and five bananas” vs. “I want one apple and five bananas”). In common language, one may be referred to as “a” or “an” (as in “a banana” or “an apple”).

However, these terms are not precise: they could refer to any single object (e.g., “I ate two carrots this morning”). In some languages like Polish or Russian there are specific words for “one”, e.g.: jeden in Polish or odin in Russian that can not be used for other numbers (Polish jedenaście means eleven).

The number 1 has 1 decimal representation. That is, the number 1 can be written in 1 ways as a decimal, as 100.

The number 1 is equal to 0.1, 10-1, 0.01 and 0.001.

1 was the first digit to be used for counting and writing numbers by humans. It was also used by ancient cultures such as Mayans, Babylonians and Chinese.

Last modified: August 2, 2022