#### Answer

12 is:
a natural number
a whole number
an integer
a rational number
a real number

#### Work Step by Step

RECALL:
(i) Natural (or Counting) Numbers are $1, 2, 3, ...$
(ii) Whole Numbers are $0, 1, 2, 3, ...$
(ii) Integers are $..., -3, -2, -1, 0, 1, 2, 3, ...$
(iv) Rational Numbers are numbers that can be expressed as a quotient of two integers.
(v) Irrational Numbers are numbers that cannot be expressed as a quotient of two integers.
(vi) Real Numbers are the set of all rational and irrational numbers.
Thus, the number 12 is
a natural number,
a whole number,
an integer,
a rational number, and
a real number.