What is the value of $123456^{2}-123455 \times 123457$ ?
Let $x=123456$.

Thus, $x-1=123455$ and $x+1=123457$.

Therefore,

$$
123456^{2}-123455 \times 123457=x^{2}-(x-1)(x+1)=x^{2}-\left(x^{2}-1\right)=1
$$

ANSWER: 1