Step 1: Align the numbers by their decimal points. $$ \begin{align} &\quad 30.900 \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline \end{align} $$ Step 2: Add the numbers column by column, starting from the rightmost digit. Adding the thousandths column ($0+0+9+9+9$): $0+0+9+9+9 = 27$. Write down 7 and carry over 2. $$ \begin{align} &\quad 30.90\overset{2}{0} \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline &\quad \phantom{00.00}7 \end{align} $$ Adding the hundredths column ($0+9+0+3+0+2$ (carry-over)): $0+9+0+3+0+2 = 14$. Write down 4 and carry over 1. $$ \begin{align} &\quad 30.9\overset{1}{0}\overset{2}{0} \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline &\quad \phantom{00.0}47 \end{align} $$ Adding the tenths column ($9+0+3+0+0+1$ (carry-over)): $9+0+3+0+0+1 = 13$. Write down 3 and carry over 1. $$ \begin{align} &\quad 30.\overset{1}{9}\overset{1}{0}\overset{2}{0} \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline &\quad \phantom{00.}347 \end{align} $$ Adding the ones column ($0+3+0+0+0+1$ (carry-over)): $0+3+0+0+0+1 = 4$. Write down 4. $$ \begin{align} &\quad 3\overset{1}{0}.\overset{1}{9}\overset{1}{0}\overset{2}{0} \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline &\quad \phantom{0}4.347 \end{align} $$ Adding the tens column ($3+0+0+0+0$): $3+0+0+0+0 = 3$. Write down 3. $$ \begin{align} &\quad 3\overset{1}{0}.\overset{1}{9}\overset{1}{0}\overset{2}{0} \\ &\quad \phantom{0}3.090 \\ &\quad \phantom{0}0.309 \\ &\quad \phantom{0}0.039 \\ &+ \quad 0.009 \\ \hline &\quad 34.347 \end{align} $$ The sum is $34.347$. The final answer is $\boxed{34.347}$.