一、口算。
77 + 6 =
18 + 7 =
66 - 16 + 40 =
90 - 60 =
66 - 5 =
22 - 11 - 2 =
81 - 8 =
15 - 8 =
53 + 8 - 20 =
44 + 4 =
40 + 10 =
24 - 5 + 20 =
21 + 18 =
46 + 7 =
48 - 25 + 7 =
35 + 12 =
81 - 61 =
80 - 20 - 8 =
49 - 18 =
88 - 66 =
33 + 11 - 4 =
32 - 8 =
76 - 62 =
77 - 25 + 30 =
36 + 4 =
26 + 22 =
62 - 30 + 8 =
85 - 33 =
56 + 13 =
13 + 25 + 30 =

83
25
90
30
61
9
73
7
41
48
50
39
39
53
30
47
20
52
31
22
40
24
14
82
40
48
40
52
69
68

二、找规律，填一填。
1.
$\begin{matrix} &76 \\35 &&41 \end{matrix}$
$\begin{matrix} &77 \\50 &&27 \end{matrix}$
$\begin{matrix} & \\21 &&17 \end{matrix}$
$\begin{matrix} &66 \\ &&23 \end{matrix}$
2.
$\begin{matrix} &24 \\56 &&32 \end{matrix}$
$\begin{matrix} &18 \\39 &&21 \end{matrix}$
$\begin{matrix} &32 \\68 && \end{matrix}$
$\begin{matrix} &21 \\ &&35 \end{matrix}$

1. 38 43
2. 36 56