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Home > CCA > Chapter 3 > Lesson 3.2.4 > Problem 3-74


Are the odd numbers a closed set under addition? Justify your conclusion.

A set of numbers is closed under an operation if the operation cannot be used with numbers from the set to get a number not in the set.

Can you add odd numbers together to get a number that is not odd?

Odd numbers are not a closed set under addition. Some examples:

and are odd, is even
, and are odd, is even
is odd, is even