1. $\begin{array}{r}
&9\\
&8\\
+\!\!\!\!\!\,&7\\
\hline
\end{array}$
Answer: 24
Explanation:
$\begin{array}{l}
9 + 8 + 7 &= 9 + (8 + 7)\\
&= 9 + 15\\
&= 24
\end{array}$
2. $\begin{array}{r}
&5\\
&9\\
+\!\!\!\!\!\,&1\\
\hline
\end{array}$
Answer: 15
Explanation:
$\begin{array}{l}
5 + 9 + 1 &= 5 + (9 + 1)\\
&= 5 + 10\\
&= 15
\end{array}$
3. $\begin{array}{r}
&7\\
&5\\
+\!\!\!\!\!\,&9\\
\hline
\end{array}$
Answer: 21
Explanation:
$\begin{array}{l}
7 + 5 + 9 &= 7 + (5 + 9)\\[6px]
&= 7 + 14\\[6px]
&= 21
\end{array}$
4. $\begin{array}{r}
&6\\
&3\\
+\!\!\!\!\!\,&8\\
\hline
\end{array}$
Answer: 17
Explanation:
$\begin{array}{l}
6 + 3 + 8 &= 6 + (3 + 8)\\[6px]
&= 6 + 11\\[6px]
&= 17
\end{array}$
5. $\begin{array}{r}
&4\\
&9\\
+\!\!\!\!\!\,&7\\
\hline
\end{array}$
Answer: 20
Explanation:
$\begin{array}{l}
4 + 9 + 7 &= 4 + (9 + 7)\\[6px]
&= 4 + 16\\[6px]
&= 20
\end{array}$
6. $\begin{array}{r}
&8\\
&8\\
+\!\!\!\!\!\,&4\\
\hline
\end{array}$
Answer: 20
Explanation:
$\begin{array}{l}
8 + 8 + 4 &= (8 + 8) + 4\\[6px]
&= 16 + 4\\[6px]
&= 20
\end{array}$
7. $\begin{array}{r}
&5\\
&5\\
+\!\!\!\!\!\,&9\\
\hline
\end{array}$
Answer: 19
Explanation:
$\begin{array}{l}
5 + 5 + 9 &= (5 + 5) + 9\\[6px]
&= 10 + 9\\[6px]
&= 19
\end{array}$
8. $\begin{array}{r}
&6\\
&6\\
+\!\!\!\!\!\,&4\\
\hline
\end{array}$
Answer: 16
Explanation:
$\begin{array}{l}
4 + 5 + 6 &= 6 + (6 + 4)\\[6px]
&= 6 + 10\\[6px]
&= 16
\end{array}$
9. $\begin{array}{r}
&7\\
&7\\
+\!\!\!\!\!\,&8\\
\hline
\end{array}$
Answer: 22
Explanation:
$\begin{array}{l}
7 + 7 + 8 &= 8 + (7 + 7)\\[6px]
&= 8 + 14\\[6px]
&= 22
\end{array}$
10. $\begin{array}{r}
&3\\
&3\\
+\!\!\!\!\!\,&9\\
\hline
\end{array}$
Answer: 15
Explanation:
$\begin{array}{l}
3 + 3 + 9 &= (3 + 3) + 9)\\[6px]
&= 6 + 9\\[6px]
&= 15
\end{array}$