Final answer:
The numbers on a telephone keypad are best described as whole numbers or integers because they consist of the non-negative digits from 0 to 9, without any fractions or irrational numbers.
Step-by-step explanation:
The numbers displayed on a telephone keypad are all whole numbers from 0 to 9. Every digit on the telephone keypad is a whole number because whole numbers include all natural numbers plus zero; that is, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. These are also integers because integers are a set of numbers that include zero, the natural numbers, and their additive inverses (negative numbers), though in the context of a telephone keypad, we only use non-negative integers (0-9).
Rational numbers are numbers that can be expressed as a fraction where both the numerator and denominator are integers, and the denominator is not zero. Real numbers include all rational and irrational numbers. But since the numbers on a keypad are not fractions or irrational, they are not uniquely classified in these sets in the context of this question. Therefore, the best description for the set that includes the numbers on a telephone keypad is whole numbers or integers.