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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)
91
×
89
(2)
2
77
(3)
2
38
(4)
92
×
88
(5)
93
×
87
(6)
88
×
92
(7)
2
32
(8)
2
39
(9)
41
×
39
(10)
2
88
(11)
2
68
(12)
49
×
51
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
91
×
89
2
2
=
(
90
+
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(2)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
+
3
=
6400
−
480
+
9
=
5929
(3)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
+
2
=
1600
−
160
+
4
=
1444
(4)
92
×
88
2
2
=
(
90
+
2
)
(
90
−
2
)
=
90
−
2
=
8100
−
4
=
8096
(5)
93
×
87
2
2
=
(
90
+
3
)
(
90
−
3
)
=
90
−
3
=
8100
−
9
=
8091
(6)
88
×
92
2
2
=
(
90
−
2
)
(
90
+
2
)
=
90
−
2
=
8100
−
4
=
8096
(7)
2
32
2
2
2
=
(
30
+
2
)
=
30
+
2
×
30
×
2
+
2
=
900
+
120
+
4
=
1024
(8)
2
39
2
2
2
=
(
40
−
1
)
=
40
−
2
×
40
×
1
+
1
=
1600
−
80
+
1
=
1521
(9)
41
×
39
2
2
=
(
40
+
1
)
(
40
−
1
)
=
40
−
1
=
1600
−
1
=
1599
(10)
2
88
2
2
2
=
(
90
−
2
)
=
90
−
2
×
90
×
2
+
2
=
8100
−
360
+
4
=
7744
(11)
2
68
2
2
2
=
(
70
−
2
)
=
70
−
2
×
70
×
2
+
2
=
4900
−
280
+
4
=
4624
(12)
49
×
51
2
2
=
(
50
−
1
)
(
50
+
1
)
=
50
−
1
=
2500
−
1
=
2499