Which set is closed under subtraction?

Rational numbers are closed under subtraction because the difference of any two rational numbers is also rational. For example, 3/4 − 1/2 = 1/4, which is rational. Whole numbers and natural numbers can give a negative result, and irrational numbers can subtract to give a rational result, such as √2 − √2 = 0.

AI-written and checked against the verified answer.