一、口算。
15 - 7 = 65 - 4 = 89 - 7 = 82 - 60 + 6 =
16 - 8 = 26 - 2 = 75 - 4 = 75 - 5 + 8 =
14 - 6 = 99 - 8 = 96 - 60 = 46 - 6 + 35 =

15 - 7 = 8
65 - 4 = 61
89 - 7 = 82
82 - 60 + 6 = 22 + 6 = 28
16 - 8 = 8
26 - 2 = 24
75 - 4 = 71
75 - 5 + 8 = 70 + 8 = 78
14 - 6 = 8
99 - 8 = 91
96 - 60 = 36
46 - 6 + 35 = 40 + 35 = 75

二、算一算。

$\begin{array}{|c|c|} \hline 49 & \\ \hline 55 & \\ \hline 28 & - 5 = \\ \hline 67 & \\ \hline 36 & \\ \hline 78 & \\ \hline \end{array}$ $\begin{array}{|c|c|} \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline \end{array}$ $\begin{array}{|c|c|} \hline 56 & \\ \hline 68 & \\ \hline 73 & - 40 = \\ \hline 85 & \\ \hline 49 & \\ \hline 93 & \\ \hline \end{array}$ $\begin{array}{|c|c|} \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline & \\ \hline \end{array}$

$49-5=44$
$55-5=50$
$28-5=23$
$67-5=62$
$36-5=31$
$78-5=73$
$56-40=16$
$68-40=28$
$73-40=33$
$85-40=45$
$49-40=9$
$93-40=53$

三、想一想，填一填。
1. 71 - 4 = $□$ 想：先算 11 减()得()，
$\begin{array}{c} \boxed{}\\ 11\\ \boxed{} \end{array}$ 再算( )加( )得( )。

2. 64 - 7 = $□$ 想：先算 14 减()得()，


$\begin{array}{c} \boxed{}\\ 14\\ \boxed{} \end{array}$ 再算( )加( )得( )。
3. 34 - 9 = $□$ 先算：$□$ - $□$ = $□$ 再算：$□$ + $□$ = $□$
26 - 7 = $□$ 先算：$□$ - $□$ = $□$ 再算：$□$ + $□$ = $□$

1. $71 - 4 = \boxed{67}$
$\begin{array}{c} \boxed{60}\\ 11\\ \boxed{4} \end{array}$
想：先算11减(4)得(7)，
再算(60)加(7)得(67)。
2. $64 - 7 = \boxed{57}$
$\begin{array}{c} \boxed{50}\\ 14\\ \boxed{7} \end{array}$
想：先算14减(7)得(7)，
再算(50)加(7)得(57)。
3. $34 - 9 = \boxed{25}$
先算：$\boxed{14} - \boxed{9} = \boxed{5}$
再算：$\boxed{20} + \boxed{5} = \boxed{25}$
$26 - 7 = \boxed{19}$
先算：$\boxed{16} - \boxed{7} = \boxed{9}$
再算：$\boxed{10} + \boxed{9} = \boxed{19}$