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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
41
(2)
79
×
81
(3)
69
×
71
(4)
69
×
71
(5)
2
38
(6)
77
×
83
(7)
2
61
(8)
18
×
22
(9)
2
77
(10)
2
31
(11)
63
×
57
(12)
79
×
81
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
41
2
2
2
=
(
40
＋
1
)
=
40
＋
2
×
40
×
1
＋
1
=
1600
＋
80
＋
1
=
1681
(2)
79
×
81
2
2
=
(
80
−
1
)
(
80
＋
1
)
=
80
−
1
=
6400
−
1
=
6399
(3)
69
×
71
2
2
=
(
70
−
1
)
(
70
＋
1
)
=
70
−
1
=
4900
−
1
=
4899
(4)
69
×
71
2
2
=
(
70
−
1
)
(
70
＋
1
)
=
70
−
1
=
4900
−
1
=
4899
(5)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
＋
2
=
1600
−
160
＋
4
=
1444
(6)
77
×
83
2
2
=
(
80
−
3
)
(
80
＋
3
)
=
80
−
3
=
6400
−
9
=
6391
(7)
2
61
2
2
2
=
(
60
＋
1
)
=
60
＋
2
×
60
×
1
＋
1
=
3600
＋
120
＋
1
=
3721
(8)
18
×
22
2
2
=
(
20
−
2
)
(
20
＋
2
)
=
20
−
2
=
400
−
4
=
396
(9)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
＋
3
=
6400
−
480
＋
9
=
5929
(10)
2
31
2
2
2
=
(
30
＋
1
)
=
30
＋
2
×
30
×
1
＋
1
=
900
＋
60
＋
1
=
961
(11)
63
×
57
2
2
=
(
60
＋
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591
(12)
79
×
81
2
2
=
(
80
−
1
)
(
80
＋
1
)
=
80
−
1
=
6400
−
1
=
6399