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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)
92
×
88
(2)
81
×
79
(3)
2
83
(4)
2
89
(5)
31
×
29
(6)
2
27
(7)
2
83
(8)
97
×
103
(9)
49
×
51
(10)
2
39
(11)
83
×
77
(12)
2
39
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
92
×
88
2
2
=
(
90
＋
2
)
(
90
−
2
)
=
90
−
2
=
8100
−
4
=
8096
(2)
81
×
79
2
2
=
(
80
＋
1
)
(
80
−
1
)
=
80
−
1
=
6400
−
1
=
6399
(3)
2
83
2
2
2
=
(
80
＋
3
)
=
80
＋
2
×
80
×
3
＋
3
=
6400
＋
480
＋
9
=
6889
(4)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
＋
1
=
8100
−
180
＋
1
=
7921
(5)
31
×
29
2
2
=
(
30
＋
1
)
(
30
−
1
)
=
30
−
1
=
900
−
1
=
899
(6)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
＋
3
=
900
−
180
＋
9
=
729
(7)
2
83
2
2
2
=
(
80
＋
3
)
=
80
＋
2
×
80
×
3
＋
3
=
6400
＋
480
＋
9
=
6889
(8)
97
×
103
2
2
=
(
100
−
3
)
(
100
＋
3
)
=
100
−
3
=
10000
−
9
=
9991
(9)
49
×
51
2
2
=
(
50
−
1
)
(
50
＋
1
)
=
50
−
1
=
2500
−
1
=
2499
(10)
2
39
2
2
2
=
(
40
−
1
)
=
40
−
2
×
40
×
1
＋
1
=
1600
−
80
＋
1
=
1521
(11)
83
×
77
2
2
=
(
80
＋
3
)
(
80
−
3
)
=
80
−
3
=
6400
−
9
=
6391
(12)
2
39
2
2
2
=
(
40
−
1
)
=
40
−
2
×
40
×
1
＋
1
=
1600
−
80
＋
1
=
1521