The set of counting numbers refers to the set of numbers that we use to learn how to count. The set would be 1, 2, 3, 4, 5, 6, 7...............
It does not contain negative numbers. They are not decimals as well. Zero is not a counting number as well. Thus, if x belongs to the set of counting numbers, then the set that does not belong to the domain of x is
{0,1,2,3,...], {-1.-2.-3...) and {1.4.2.3 -}
