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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)
2
89
(2)
101
×
99
(3)
102
×
98
(4)
2
69
(5)
2
77
(6)
2
31
(7)
2
37
(8)
33
×
27
(9)
2
77
(10)
68
×
72
(11)
2
28
(12)
2
87
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
+
1
=
8100
−
180
+
1
=
7921
(2)
101
×
99
2
2
=
(
100
+
1
)
(
100
−
1
)
=
100
−
1
=
10000
−
1
=
9999
(3)
102
×
98
2
2
=
(
100
+
2
)
(
100
−
2
)
=
100
−
2
=
10000
−
4
=
9996
(4)
2
69
2
2
2
=
(
70
−
1
)
=
70
−
2
×
70
×
1
+
1
=
4900
−
140
+
1
=
4761
(5)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
+
3
=
6400
−
480
+
9
=
5929
(6)
2
31
2
2
2
=
(
30
+
1
)
=
30
+
2
×
30
×
1
+
1
=
900
+
60
+
1
=
961
(7)
2
37
2
2
2
=
(
40
−
3
)
=
40
−
2
×
40
×
3
+
3
=
1600
−
240
+
9
=
1369
(8)
33
×
27
2
2
=
(
30
+
3
)
(
30
−
3
)
=
30
−
3
=
900
−
9
=
891
(9)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
+
3
=
6400
−
480
+
9
=
5929
(10)
68
×
72
2
2
=
(
70
−
2
)
(
70
+
2
)
=
70
−
2
=
4900
−
4
=
4896
(11)
2
28
2
2
2
=
(
30
−
2
)
=
30
−
2
×
30
×
2
+
2
=
900
−
120
+
4
=
784
(12)
2
87
2
2
2
=
(
90
−
3
)
=
90
−
2
×
90
×
3
+
3
=
8100
−
540
+
9
=
7569