Yes.
Rational numbers are closed under addition, subtraction, multiplication. They are not closed under division, since you can't divide by zero. However, rational numbers excluding the zero are closed under division.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
Yes, it is.
Yes, the set of rational numbers is closed under addition.
No Q is not cyclic under addition.
Yes.
Yes, they can.
Yes.
Rational numbers are closed under addition, subtraction, multiplication. They are not closed under division, since you can't divide by zero. However, rational numbers excluding the zero are closed under division.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
Yes. In general, the set of rational numbers is closed under addition, subtraction, and multiplication; and the set of rational numbers without zero is closed under division.
No. The set of rational numbers is closed under addition (and multiplication).
Yes, it is.
The set of rational numbers is closed under all 4 basic operations.
Yes, the set of rational numbers is closed under addition.
Yes. They are closed under addition, subtraction, multiplication. The rational numbers WITHOUT ZERO are closed under division.