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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
72
(2)
91
×
89
(3)
2
61
(4)
2
51
(5)
2
68
(6)
41
×
39
(7)
83
×
77
(8)
2
81
(9)
2
63
(10)
2
77
(11)
2
52
(12)
63
×
57
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
72
2
2
2
=
(
70
＋
2
)
=
70
＋
2
×
70
×
2
＋
2
=
4900
＋
280
＋
4
=
5184
(2)
91
×
89
2
2
=
(
90
＋
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(3)
2
61
2
2
2
=
(
60
＋
1
)
=
60
＋
2
×
60
×
1
＋
1
=
3600
＋
120
＋
1
=
3721
(4)
2
51
2
2
2
=
(
50
＋
1
)
=
50
＋
2
×
50
×
1
＋
1
=
2500
＋
100
＋
1
=
2601
(5)
2
68
2
2
2
=
(
70
−
2
)
=
70
−
2
×
70
×
2
＋
2
=
4900
−
280
＋
4
=
4624
(6)
41
×
39
2
2
=
(
40
＋
1
)
(
40
−
1
)
=
40
−
1
=
1600
−
1
=
1599
(7)
83
×
77
2
2
=
(
80
＋
3
)
(
80
−
3
)
=
80
−
3
=
6400
−
9
=
6391
(8)
2
81
2
2
2
=
(
80
＋
1
)
=
80
＋
2
×
80
×
1
＋
1
=
6400
＋
160
＋
1
=
6561
(9)
2
63
2
2
2
=
(
60
＋
3
)
=
60
＋
2
×
60
×
3
＋
3
=
3600
＋
360
＋
9
=
3969
(10)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
＋
3
=
6400
−
480
＋
9
=
5929
(11)
2
52
2
2
2
=
(
50
＋
2
)
=
50
＋
2
×
50
×
2
＋
2
=
2500
＋
200
＋
4
=
2704
(12)
63
×
57
2
2
=
(
60
＋
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591