1. $\begin{array}{r}
&72\\
+\!\!\!\!\!\,&36\\
\hline
\end{array}$
Answer: 108
Explanation:
$\begin{array}{l}
72 + 36 &= 72 + (30 + 6)\\[6px]
&= 102 + 6\\[6px]
&= 108
\end{array}$
2. $\begin{array}{r}
&57\\
+\!\!\!\!\!\,&64\\
\hline
\end{array}$
Answer: 121
Explanation:
$\begin{array}{l}
57 + 64 &= 57 + (60 + 4)\\[6px]
&= 117 + 4\\[6px]
&= 121
\end{array}$
3. $\begin{array}{r}
&86\\
+\!\!\!\!\!\,&47\\
\hline
\end{array}$
Answer: 133
Explanation:
$\begin{array}{l}
86 + 47 &= 86 + (40 + 7)\\[6px]
&= 126 + 7\\[6px]
&= 133
\end{array}$
4. $\begin{array}{r}
&59\\
+\!\!\!\!\!\,&64\\
\hline
\end{array}$
Answer: 123
Explanation:
$\begin{array}{l}
59 + 64 &= 59 + (60 + 4)\\[6px]
&= 119 + 4\\[6px]
&= 123
\end{array}$
5. $\begin{array}{r}
&86\\
+\!\!\!\!\!\,&47\\
\hline
\end{array}$
Answer: 133
Explanation:
$\begin{array}{l}
86 + 47 &= 86 + (40 + 7)\\[6px]
&= 126 + 7\\[6px]
&= 133
\end{array}$
6. $\begin{array}{r}
&88\\
+\!\!\!\!\!\,&67\\
\hline
\end{array}$
Answer: 155
Explanation:
$\begin{array}{l}
88 + 67 &= 88 + (60 + 7)\\[6px]
&= 148 + 7\\[6px]
&= 155
\end{array}$
7. $\begin{array}{r}
&69\\
+\!\!\!\!\!\,&48\\
\hline
\end{array}$
Answer: 117
Explanation:
$\begin{array}{l}
69 + 48 &= 69 + (40 + 8)\\[6px]
&= 109 + 8\\[6px]
&= 117
\end{array}$
8. $\begin{array}{r}
&47\\
+\!\!\!\!\!\,&62\\
\hline
\end{array}$
Answer: 109
Explanation:
$\begin{array}{l}
47 + 62 &= 47 + (60 + 2)\\[6px]
&= 107 + 2\\[6px]
&= 109
\end{array}$
9. $\begin{array}{r}
&88\\
+\!\!\!\!\!\,&48\\
\hline
\end{array}$
Answer: 136
Explanation:
$\begin{array}{l}
88 + 48 &= 88 + (40 + 8)\\[6px]
&= 128 + 8\\[6px]
&= 136
\end{array}$
10. $\begin{array}{r}
&55\\
+\!\!\!\!\!\,&77\\
\hline
\end{array}$
Answer: 132
Explanation:
$\begin{array}{l}
55 + 77 &= 55 + (70 + 7)\\[6px]
&= 125 + 7\\[6px]
&= 132
\end{array}$