P is the set of even numbers that are less than 11

Is there a restriction that the set must be positive? or whole numbers? Because negative numbers can be even, which makes your set an infinite list of numbers.

Natural numbers: P = {2, 4, 6, 8, 10}

Whole numbers: P = {0, 2, 4, 6, 8, 10}

All real numbers: P = {2n; n ≤ 5}