13.338. The recording of a six-digit number starts with the digit 2. If this digit is moved from the first position to the last, keeping the order of the other five digits, the newly obtained number will be three times the original number. Find the original number.
Solution.

The original six-digit number has the form $2 \cdot 10^{5}+x$. After moving the digit 2 to the last place, we get the number $10 x+2$. According to the condition, $10 x+2=3\left(2 \cdot 10^{5}+x\right)$, from which $x=85714$.

Answer: 285714.