Yes.
No. The product of two primes cannot, by definition, be a prime.
No.
No.
Yes they are closed under multiplication, addition, and subtraction.
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.
Is { 0, 20 } closed under multiplication
Because it is a product of real numbers. And the set of real numbers is closed under multiplication.
A set is closed under multiplication if for any two elements, x and y, in the set, their product, x*y, is also a member of the set.
No. The product of two primes cannot, by definition, be a prime.
Yes.natural numbers are closed under multiplication.It means when the operation is done with natural numbers in multiplication the sum of two numbers is always the natural number.
No.
Rational numbers are closed under multiplication, because if you multiply any rational number you will get a pattern. Rational numbers also have a pattern or terminatge, which is good to keep in mind.
If you can never, by multiplying two whole numbers, get anything but another whole number back as your answer, then, YES, the set of whole numbers must be closed under multiplication.
No.
No.
No.
Because the product of any two elements is also an element of the set.