Posted by Mike on .
If 10 is removed from the set of whole numbers, is the set closed with respect to addition? Explain why or why not.

math 
MathMate,
Is the set closed under this operation?
5+5 = 10
(note that 5 ∈ℤ' and 10 ∉ℤ', where ℤ' is ℤ\10)