Task B-1.1. Calculate $\frac{1234321234321 \cdot 2468642468641-1234321234320}{1234321234320 \cdot 2468642468641+1234321234321}$.
Solution. Let $n=1234321234321$.

Then the given expression is equivalent to the expression

$$
\begin{aligned}
& \frac{n \cdot(2 n-1)-(n-1)}{(n-1) \cdot(2 n-1)+n}= \\
& \frac{2 n^{2}-n-n+1}{2 n^{2}-2 n-n+1+n}= \\
& \frac{2 n^{2}-2 n+1}{2 n^{2}-2 n+1}=1
\end{aligned}
$$