To any set that contains it! It belongs to {sqrt(30)}, or {45, sqrt(30), pi, -3/7}, or irrational numbers, or real numbers between -6 and 6, or all real numbers or complex numbers, etc.
It can be element of: Rational numbers or Real numbers
17 belongs to the set of prime numbers
The rational numbers, the real numbers and sets of higher order which contain the reals such as the complex numbers.
-12 belongs to at least the sets of all numbers, of integers and negative integers, of rational numbers and negative rational numbers, and all negative numbers.
real numbers, irrational numbers, ...
Complex numbers.
The sets of numbers that are the Square root of 5 are: 25 125
Among other things, it belongs to the following sets: positive numbers; irrational numbers; algebraic numbers.
It is an irrational number, and therefore a real number.
Rational numbers
To any set that contains it! It belongs to {sqrt(30)}, or {45, sqrt(30), pi, -3/7}, or irrational numbers, or real numbers between -6 and 6, or all real numbers or complex numbers, etc.
The LCM of 3 and 9 is 9.
Natural numbers.
It can be element of: Rational numbers or Real numbers
17 belongs to the set of prime numbers
1.18 is a number and number do not contain any sets (of any kind).