Formula to get result as $0$ for a variable assigned as $1$.

Question

I actually want to perform bitwise not operating in normal calculation mode in my Casio fx-991 ex.

I want a formula which consists of one variable, which can be assigned with either $0$ or $1$. The formula's result should be $0$ if the variable is assigned with $1$ and should result in $1$ if the variable is assigned with $0$.

Answer 1

$f(x)=1−x$ works. This doesn't have much to do with bitwise not, though.