Question

Select from the drop-down menus to correctly identify whether the given operation is closed or not closed with respect to each set of numbers.

Real numbers are (closed, not closed) under multiplication.

Irrational numbers are (closed, not closed) under division.

Integers are (closed, not closed) under subtraction.

Positive rational numbers are (closed, not closed) under addition.

Answer 1

closed, not closed, closed

Answer 2

closed, not closed, closed, closed