* Use the even and odd predicates, if the language provides them.
* Check the least significant digit. With binary integers, ''i [[bitwise operations|bitwise-and]] 1'' equals 0 [[wikt:iff|iff]] ''i'' is even, or equals 1 iff ''i'' is odd.
* Divide ''i'' by 2. The remainder equals 0 iff ''i'' is even. The remainder equals +1 or -1 iff ''i'' is odd.