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1. There are \(512\) subsets.

2. \(\displaystyle {9 \choose 5} = 126\text{.}\)

3. \(2^4 = 16\text{.}\) (Note, if you wish to exclude the empty set - it does not contain odd numbers, but no evens either - then you could subtract 1).

4. \(\displaystyle 256\text{.}\)