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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
51
(2)
2
28
(3)
2
71
(4)
2
61
(5)
2
71
(6)
2
87
(7)
49
×
51
(8)
68
×
72
(9)
81
×
79
(10)
27
×
33
(11)
62
×
58
(12)
19
×
21
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
51
2
2
2
=
(
50
＋
1
)
=
50
＋
2
×
50
×
1
＋
1
=
2500
＋
100
＋
1
=
2601
(2)
2
28
2
2
2
=
(
30
−
2
)
=
30
−
2
×
30
×
2
＋
2
=
900
−
120
＋
4
=
784
(3)
2
71
2
2
2
=
(
70
＋
1
)
=
70
＋
2
×
70
×
1
＋
1
=
4900
＋
140
＋
1
=
5041
(4)
2
61
2
2
2
=
(
60
＋
1
)
=
60
＋
2
×
60
×
1
＋
1
=
3600
＋
120
＋
1
=
3721
(5)
2
71
2
2
2
=
(
70
＋
1
)
=
70
＋
2
×
70
×
1
＋
1
=
4900
＋
140
＋
1
=
5041
(6)
2
87
2
2
2
=
(
90
−
3
)
=
90
−
2
×
90
×
3
＋
3
=
8100
−
540
＋
9
=
7569
(7)
49
×
51
2
2
=
(
50
−
1
)
(
50
＋
1
)
=
50
−
1
=
2500
−
1
=
2499
(8)
68
×
72
2
2
=
(
70
−
2
)
(
70
＋
2
)
=
70
−
2
=
4900
−
4
=
4896
(9)
81
×
79
2
2
=
(
80
＋
1
)
(
80
−
1
)
=
80
−
1
=
6400
−
1
=
6399
(10)
27
×
33
2
2
=
(
30
−
3
)
(
30
＋
3
)
=
30
−
3
=
900
−
9
=
891
(11)
62
×
58
2
2
=
(
60
＋
2
)
(
60
−
2
)
=
60
−
2
=
3600
−
4
=
3596
(12)
19
×
21
2
2
=
(
20
−
1
)
(
20
＋
1
)
=
20
−
1
=
400
−
1
=
399