Add

(1) 1117

Explanation

Add units first

Add the bold numbers in the ones column first. Think: (9 + 1) + 7 = 10 + 7 = 17. Write the 7 and carry the 1. 

\[
\begin{array}{r}
\phantom{+}2\phantom{0}\overset{\color{red}{1}}{0}\phantom{0}\color{red}{1} \\
+\phantom{0}8\phantom{0}6\phantom{0}\color{red}{7} \\
+\phantom{0}0\phantom{0}4\phantom{0}\color{red}{9} \\
\hline
\phantom{0}\phantom{0}\phantom{0}\phantom{0}\phantom{0}\color{red}{7}\\
\end{array}
\]

 Add tens next

Add the bold numbers in the tens column. Think: (6 + 4) + 1 = 10 + 1 =  11. Write the 1 and carry the 1. 

\[
\begin{array}{r}
\phantom{+}\overset{\color{red}{1}}{2}\phantom{0}\overset{1}{\color{red}{0}}\phantom{0}1 \\
+\phantom{0}8\phantom{0}\color{red}{6}\phantom{0}7 \\
+\phantom{0}0\phantom{0}\color{red}{4}\phantom{0}9 \\
\hline
\phantom{0}\phantom{0}\phantom{0}\phantom{0}\color{red}{1}\phantom{0}7\\
\end{array}
\]

Add hundreds last

Add the bold numbers in the hundreds column. Think: (2 + 8) + 1 = 10 + 1 = 11.

\[
\begin{array}{r}
\phantom{+}\overset{1}{\color{red}{2}}\phantom{0}\overset{1}{0}\phantom{0}1 \\
+\phantom{0}\color{red}{8}\phantom{0}6\phantom{0}7 \\
+\phantom{0}\color{red}{0}\phantom{0}4\phantom{0}9 \\
\hline
\phantom{0}\phantom{0}1\phantom{0}1\phantom{0}1\phantom{0}7\\
\end{array}
\]

The sum would be written like that

\[
\begin{array}{r}
\phantom{+}2\phantom{0}0\phantom{0}1 \\
+\phantom{0}8\phantom{0}6\phantom{0}7 \\
+\phantom{0}0\phantom{0}4\phantom{0}9 \\
\hline
1\phantom{0}1\phantom{0}1\phantom{0}7 \\
\end{array}
\]

The sum is 1117