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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)
78
×
82
(2)
77
×
83
(3)
91
×
89
(4)
2
29
(5)
2
27
(6)
2
89
(7)
91
×
89
(8)
2
58
(9)
63
×
57
(10)
2
89
(11)
62
×
58
(12)
92
×
88
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
78
×
82
2
2
=
(
80
−
2
)
(
80
+
2
)
=
80
−
2
=
6400
−
4
=
6396
(2)
77
×
83
2
2
=
(
80
−
3
)
(
80
+
3
)
=
80
−
3
=
6400
−
9
=
6391
(3)
91
×
89
2
2
=
(
90
+
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(4)
2
29
2
2
2
=
(
30
−
1
)
=
30
−
2
×
30
×
1
+
1
=
900
−
60
+
1
=
841
(5)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
+
3
=
900
−
180
+
9
=
729
(6)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
+
1
=
8100
−
180
+
1
=
7921
(7)
91
×
89
2
2
=
(
90
+
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(8)
2
58
2
2
2
=
(
60
−
2
)
=
60
−
2
×
60
×
2
+
2
=
3600
−
240
+
4
=
3364
(9)
63
×
57
2
2
=
(
60
+
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591
(10)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
+
1
=
8100
−
180
+
1
=
7921
(11)
62
×
58
2
2
=
(
60
+
2
)
(
60
−
2
)
=
60
−
2
=
3600
−
4
=
3596
(12)
92
×
88
2
2
=
(
90
+
2
)
(
90
−
2
)
=
90
−
2
=
8100
−
4
=
8096