Question

Identify the number that does not belong with the other three. Explain your reasoning. 26.6 repeating 6, square root 48, negative 51 over 2, negative 55.1

Answer 1

Each entry below is a set of numbers

natural numbers - the counting numbers: 1, 2, 3, 4, ...

whole numbers - the counting numbers and zero: 0, 1, 2, 3, 4, ...

integers - the natural numbers, zero, and the negatives of the natural numbers:
..., -3, -2, -1, 0, 1, 2, 3, ...

rational numbers - numbers that can be written as a fraction of integers
this includes all the sets above, all terminating decimals, and all non-terminating,
repeating decimals

irrational numbers - a number that is not rational
this includes all non-terminating, non-repeating decimals

The sets of rational and irrational numbers combined form the set of real numbers.