The resulting decimal will be either repeating or terminating. The denominator of the fraction cannot be zero. The notation Q means Quotient . I is the system for any number that cannot be written as a fraction where the numerator and denominator are integers. Since irrational numbers cannot be expressed as a fraction they form decimals that are neither repeating nor terminating.
R is the real numbers system and includes the rational and irrational numbers.
Consequently, Z- means only negative numbers of Z .