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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)
88
×
92
(2)
72
×
68
(3)
69
×
71
(4)
2
89
(5)
51
×
49
(6)
2
71
(7)
2
27
(8)
91
×
89
(9)
2
73
(10)
2
63
(11)
39
×
41
(12)
31
×
29
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
88
×
92
2
2
=
(
90
−
2
)
(
90
＋
2
)
=
90
−
2
=
8100
−
4
=
8096
(2)
72
×
68
2
2
=
(
70
＋
2
)
(
70
−
2
)
=
70
−
2
=
4900
−
4
=
4896
(3)
69
×
71
2
2
=
(
70
−
1
)
(
70
＋
1
)
=
70
−
1
=
4900
−
1
=
4899
(4)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
＋
1
=
8100
−
180
＋
1
=
7921
(5)
51
×
49
2
2
=
(
50
＋
1
)
(
50
−
1
)
=
50
−
1
=
2500
−
1
=
2499
(6)
2
71
2
2
2
=
(
70
＋
1
)
=
70
＋
2
×
70
×
1
＋
1
=
4900
＋
140
＋
1
=
5041
(7)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
＋
3
=
900
−
180
＋
9
=
729
(8)
91
×
89
2
2
=
(
90
＋
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(9)
2
73
2
2
2
=
(
70
＋
3
)
=
70
＋
2
×
70
×
3
＋
3
=
4900
＋
420
＋
9
=
5329
(10)
2
63
2
2
2
=
(
60
＋
3
)
=
60
＋
2
×
60
×
3
＋
3
=
3600
＋
360
＋
9
=
3969
(11)
39
×
41
2
2
=
(
40
−
1
)
(
40
＋
1
)
=
40
−
1
=
1600
−
1
=
1599
(12)
31
×
29
2
2
=
(
30
＋
1
)
(
30
−
1
)
=
30
−
1
=
900
−
1
=
899