To any set that contains it!
It belongs to {1.18},
or {45, sqrt(2), pi, 1.18, -3/7},
or all numbers between -2 and 453,
or improper fractions (1.18 = 19/50],
or rational numbers,
or real numbers,
or complex numbers,
etc.
10 belongs to the natural integer numbers
173 belongs to the set of positive natural numbers and it also belongs to the set of prime numbers.
Prime and odd numbers
It belongs to the set of prime numbers
The number -4 belongs to the set of all integers. It also belongs to the rationals, reals, complex numbers.
It belongs to the set ofrational numbers,decimal fractions,improper fractions (in decimal form),real numbers,complex numbers,quaternions.
Rational numbers and Real numbers
30 belongs to the set of natural numbers
Such set of numbers cannot exist.
Real numbers; also the rational numbers.
10 belongs to the set "natural numbers", but it can also belong to whole numbers, and rational numbers
Any number that can be written as a fraction belongs to the set of rational numbers.