Question 24
It is known that $\overline{ab}$ is a 2-digit number. By writing “1” behind it, it becomes a 3-digit number $\overline{ab1}$. By writing “1” in front, it becomes another 3-digit number $\overline{1ab}$. Given that the difference between $\overline{ab1}$ and $\overline{1ab}$ is 414, which digit does b represent?