Use the "weirdo" method to explain why the amounts of subsets with even/odd elements are equal.
56828
A combinatorial proof that the alternating sum of binomial coefficients is zero
58205
$ N $ normal in a finite group $ G $, $ |N| = 5 $ and $ |G| $ odd. Why is $ N \subseteq Z(G) $?
153072
Guessing a subset of $\{1,...,N\}$
114796
Direct proof that the product of odd integers is odd
104010
The number of partitions of $n$ into distinct parts equals the number of partitions of $n$ into odd parts
101573
Subtracting even and odd binomial coefficients?
53194
Prove : $p$(n│even number of ODD parts)=$p$(n│distinct parts ,number of ODD parts is even )
123065
Pretty way to group elements at odd and even positions
129693
An interesting problem with "decomposing" natural numbers.
75723
Odd Binomial Coefficients?
89474
every permutation is either even or odd,but not both
91951
How do I check if an integer is even or odd?
74447
How do I divide a function into even and odd sections?
128834
Proving the number of even and odd permutations of a subgroup $H<S_{n}$ are equal, provided $H$ is not contained in $A_{n}$
5230
Why can a 1 element set be a member of another set but not a subset of it?
135351
$C(n,p)$: even or odd?
142724
Prove that for all integers $x$ and $y$, $x - y$ is odd if and only if $x + y$ is odd.