DK-GEORGMOHR 1997

Let $n =123456789101112 ... 998999$ be the natural number where is obtained by writing the natural numbers from $1$ to $999$ one after the other. What is the $1997$ -th digit number in $n$ ?

About pentagon $ABCDE$ is known that angle $A$ and angle $C$ are right and that the sides $| AB | = 4$ , $| BC | = 5$ , $| CD | = 10$ , $| DE | = 6$ . Furthermore, the point $C'$ that appears by mirroring $C$ in the line $BD$ , lies on the line segment $AE$ . Find angle $E$ .

Find all pairs $x,y$ of natural numbers that satisfy the equation $$x^2-xy+2x-3y=1997$$