|This article needs additional citations for verification. (May 2012)|
A round number is mathematically defined as the product of a considerable number of comparatively small factors as compared to its neighbouring numbers, such as 24 = 2*2*2*3 (4 factors, as opposed to 3 factors for 27; 2 factors for 21, 22, 25, and 26; and 1 factor for 23).
A round number is informally considered to be an integer that ends with one or more zeroes (0). A number ending in 5, might be considered in a way more "round" than one ending in 0. For example, a non-integer such as 2.5, might be seen as more round than 2.497 (esp. written 2.500).
Numbers can also be considered "round" in numbering systems other than decimal (base 10). For example, the number 1024 would not be considered "round" in decimal, but the same number ends with a zero in several other numbering systems including binary (base 2: 10000000000), octal (base 8: 2000), and hexadecimal (base 16: 400).
- "MathWorld's definition of a round number". Retrieved 2012-05-03.
- based on Hardy, G. H. "Round Numbers." Ch. 3 in Ramanujan: Twelve Lectures on Subjects Suggested by His Life and Work, 3rd ed. New York: Chelsea, pp. 48–57, 1999.