Browse Definitions:
Definition

# random numbers

Random numbers are numbers that occur in a sequence such that two conditions are met: (1) the values are uniformly distributed over a defined interval or set, and (2) it is impossible to predict future values based on past or present ones. Random numbers are important in statistical analysis and probability theory.

The most common set from which random numbers are derived is the set of single-digit decimal numbers {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}. The task of generating random digits from this set is not trivial. A common scheme is the selection (by means of a mechanical escape hatch that lets one ball out at a time) of numbered ping-pong balls from a set of 10, one bearing each digit, as the balls are blown about in a container by forced-air jets. This method is popular in lotteries. After each number is selected, the ball with that number is returned to the set, the balls are allowed to blow around for a minute or two, and then another ball is allowed to escape.

Sometimes the digits in the decimal expansions of irrational numbers are used in an attempt to obtain random numbers. Most whole numbers have irrational square roots, so entering a string of six or eight digits into a calculator and then hitting the square root button can provide a sequence of digits that seems random. Other algorithms have been devised that supposedly generate random numbers. The problem with these methods is that they violate condition (2) in the definition of randomness. The existence of any number-generation algorithm produces future values based on past and/or current ones. Digits or numbers generated in this manner are called pseudorandom.

Statisticians, mathematicians, and scientists have long searched for the ideal source of random numbers. One of the best methods is the sampling of electromagnetic noise. This noise, generated by the chaotic movements of electrons, holes, or other charge carriers in materials and in space, is thought to be as close to "totally random" as any observable phenomenon.

This was last updated in September 2005

#### Start the conversation

Send me notifications when other members comment.

## SearchCompliance

• ### risk map (risk heat map)

A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces.

• ### internal audit (IA)

An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

• ### pure risk (absolute risk)

Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

## SearchSecurity

• ### FIDO (Fast Identity Online)

FIDO (Fast ID Online) is a set of technology-agnostic security specifications for strong authentication. FIDO is developed by the...

• ### cryptanalysis

Cryptanalysis is the study of ciphertext, ciphers and cryptosystems with the aim of understanding how they work and finding and ...

• ### Trojan horse (computing)

In computing, a Trojan horse is a program that appears harmless, but is, in fact, malicious.

## SearchHealthIT

• ### HITECH (Health Information Technology for Economic and Clinical Health) Act of 2009

The HITECH (Health Information Technology for Economic and Clinical Health) Act of 2009 is legislation that was created to ...

• ### Epic Systems

Epic Systems is one of the largest providers of health information technology, used primarily by large U.S. hospitals and health ...

• ### accountable care organization (ACO)

An accountable care organization (ACO) is an association of hospitals, healthcare providers and insurers in which all parties ...

## SearchDisasterRecovery

• ### business continuity and disaster recovery (BCDR)

Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

• ### business continuity plan (BCP)

A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

• ### call tree

A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

## SearchStorage

• ### personal cloud storage (PCS)

Personal cloud storage (PCS) enables users to store data, photos, music, videos and other files on a local network-attached ...

• ### cloud SLA (cloud service-level agreement)

A cloud SLA (cloud service-level agreement) is an agreement between a cloud service provider and a customer that ensures a ...

• ### wear leveling

Wear leveling is a process that is designed to extend the life of solid-state storage devices.

## SearchSolidStateStorage

• ### hybrid hard disk drive (HDD)

A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.

Close