In statistics, a random number is a number that belongs to a numerical series and cannot be predicted from the previous members of the series. The concept of random number is a concept related to the numerical series to which the number belongs. A number can be random in one number series and not random in another.
The strings of random numbers can be generated by random processors such as roulette. Pseudo-random sequences, that is, sequences that can be predicted by knowing the initial number, can be generated by algorithms and are used for practical purposes.