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©2026 数学クラブ http://sugaku.club/
月 日（ ）
● 次の計算をしなさい
[1C1-00]
(1)
42
×
38
(2)
2
89
(3)
2
67
(4)
73
×
67
(5)
2
73
(6)
2
82
(7)
2
72
(8)
2
89
(9)
103
×
97
(10)
17
×
23
(11)
32
×
28
(12)
2
21
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
42
×
38
2
2
=
(
40
＋
2
)
(
40
−
2
)
=
40
−
2
=
1600
−
4
=
1596
(2)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
＋
1
=
8100
−
180
＋
1
=
7921
(3)
2
67
2
2
2
=
(
70
−
3
)
=
70
−
2
×
70
×
3
＋
3
=
4900
−
420
＋
9
=
4489
(4)
73
×
67
2
2
=
(
70
＋
3
)
(
70
−
3
)
=
70
−
3
=
4900
−
9
=
4891
(5)
2
73
2
2
2
=
(
70
＋
3
)
=
70
＋
2
×
70
×
3
＋
3
=
4900
＋
420
＋
9
=
5329
(6)
2
82
2
2
2
=
(
80
＋
2
)
=
80
＋
2
×
80
×
2
＋
2
=
6400
＋
320
＋
4
=
6724
(7)
2
72
2
2
2
=
(
70
＋
2
)
=
70
＋
2
×
70
×
2
＋
2
=
4900
＋
280
＋
4
=
5184
(8)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
＋
1
=
8100
−
180
＋
1
=
7921
(9)
103
×
97
2
2
=
(
100
＋
3
)
(
100
−
3
)
=
100
−
3
=
10000
−
9
=
9991
(10)
17
×
23
2
2
=
(
20
−
3
)
(
20
＋
3
)
=
20
−
3
=
400
−
9
=
391
(11)
32
×
28
2
2
=
(
30
＋
2
)
(
30
−
2
)
=
30
−
2
=
900
−
4
=
896
(12)
2
21
2
2
2
=
(
20
＋
1
)
=
20
＋
2
×
20
×
1
＋
1
=
400
＋
40
＋
1
=
441