Question 1
Consider the integer $$
\begin{aligned} &N = 9 + 99 + 999 + 9999 \\ &\quad {}+ \cdots + \underbrace{99\ldots99}_{\text{321 digits}}. \end{aligned}
$$ Find the sum of the digits of $N.$
\begin{aligned} &N = 9 + 99 + 999 + 9999 \\ &\quad {}+ \cdots + \underbrace{99\ldots99}_{\text{321 digits}}. \end{aligned}
$$ Find the sum of the digits of $N.$