144−−−√ belongs to the set of perfect squares, since 144 is a perfect square.
0.121212... belongs to the set of rational numbers, since it can be expressed as a repeating decimal.
0 belongs to the set of real numbers, since it is a real number.
47−−√ belongs to the set of irrational numbers, since it cannot be expressed as a fraction.
-9 belongs to the set of integers, since it is a whole number that can be negative.
Rational number,
irrational number
whole number
integer
natural number