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©2025 数学クラブ http://sugaku.club/
月 日（ ）
● 次の計算をしなさい
[1C1-00]
(1)
71
×
69
(2)
78
×
82
(3)
78
×
82
(4)
2
27
(5)
2
42
(6)
2
32
(7)
53
×
47
(8)
42
×
38
(9)
2
38
(10)
2
29
(11)
19
×
21
(12)
98
×
102
©2025 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
71
×
69
2
2
=
(
70
＋
1
)
(
70
−
1
)
=
70
−
1
=
4900
−
1
=
4899
(2)
78
×
82
2
2
=
(
80
−
2
)
(
80
＋
2
)
=
80
−
2
=
6400
−
4
=
6396
(3)
78
×
82
2
2
=
(
80
−
2
)
(
80
＋
2
)
=
80
−
2
=
6400
−
4
=
6396
(4)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
＋
3
=
900
−
180
＋
9
=
729
(5)
2
42
2
2
2
=
(
40
＋
2
)
=
40
＋
2
×
40
×
2
＋
2
=
1600
＋
160
＋
4
=
1764
(6)
2
32
2
2
2
=
(
30
＋
2
)
=
30
＋
2
×
30
×
2
＋
2
=
900
＋
120
＋
4
=
1024
(7)
53
×
47
2
2
=
(
50
＋
3
)
(
50
−
3
)
=
50
−
3
=
2500
−
9
=
2491
(8)
42
×
38
2
2
=
(
40
＋
2
)
(
40
−
2
)
=
40
−
2
=
1600
−
4
=
1596
(9)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
＋
2
=
1600
−
160
＋
4
=
1444
(10)
2
29
2
2
2
=
(
30
−
1
)
=
30
−
2
×
30
×
1
＋
1
=
900
−
60
＋
1
=
841
(11)
19
×
21
2
2
=
(
20
−
1
)
(
20
＋
1
)
=
20
−
1
=
400
−
1
=
399
(12)
98
×
102
2
2
=
(
100
−
2
)
(
100
＋
2
)
=
100
−
2
=
10000
−
4
=
9996