Question

Whole numbers are not closed under:

• A. addition
• B. subtraction
• C. multiplication
• D. division

Answer 1

Answer: (B), (D)

division

If we add any two whole numbers, the result will be a whole number. For example, 2 + 4 = 6 and 6 is a whole number.
Therefore, whole numbers are closed under addition.

If we multiply any two whole numbers, the result will be a whole number. For example, 2 $\times$ 4 = 8 and 8 is a whole number.
Therefore, whole numbers are closed under multiplication.

But if we subtract a bigger number from a smaller number, for example 2 - 4, the result will not be a whole number.
Therefore, whole numbers are not closed under subtraction.

Similarly, if we divide zero by 10, we would get zero and if we divide 10 by zero, the result would be not defined. Therefore, whole numbers are not closed under division.