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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)
68
×
72
(2)
31
×
29
(3)
2
38
(4)
87
×
93
(5)
2
52
(6)
2
73
(7)
2
77
(8)
2
38
(9)
39
×
41
(10)
2
89
(11)
28
×
32
(12)
2
72
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
68
×
72
2
2
=
(
70
−
2
)
(
70
＋
2
)
=
70
−
2
=
4900
−
4
=
4896
(2)
31
×
29
2
2
=
(
30
＋
1
)
(
30
−
1
)
=
30
−
1
=
900
−
1
=
899
(3)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
＋
2
=
1600
−
160
＋
4
=
1444
(4)
87
×
93
2
2
=
(
90
−
3
)
(
90
＋
3
)
=
90
−
3
=
8100
−
9
=
8091
(5)
2
52
2
2
2
=
(
50
＋
2
)
=
50
＋
2
×
50
×
2
＋
2
=
2500
＋
200
＋
4
=
2704
(6)
2
73
2
2
2
=
(
70
＋
3
)
=
70
＋
2
×
70
×
3
＋
3
=
4900
＋
420
＋
9
=
5329
(7)
2
77
2
2
2
=
(
80
−
3
)
=
80
−
2
×
80
×
3
＋
3
=
6400
−
480
＋
9
=
5929
(8)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
＋
2
=
1600
−
160
＋
4
=
1444
(9)
39
×
41
2
2
=
(
40
−
1
)
(
40
＋
1
)
=
40
−
1
=
1600
−
1
=
1599
(10)
2
89
2
2
2
=
(
90
−
1
)
=
90
−
2
×
90
×
1
＋
1
=
8100
−
180
＋
1
=
7921
(11)
28
×
32
2
2
=
(
30
−
2
)
(
30
＋
2
)
=
30
−
2
=
900
−
4
=
896
(12)
2
72
2
2
2
=
(
70
＋
2
)
=
70
＋
2
×
70
×
2
＋
2
=
4900
＋
280
＋
4
=
5184