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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)
29
×
31
(2)
2
41
(3)
21
×
19
(4)
2
72
(5)
2
38
(6)
2
87
(7)
32
×
28
(8)
49
×
51
(9)
53
×
47
(10)
2
62
(11)
2
88
(12)
2
27
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
29
×
31
2
2
=
(
30
−
1
)
(
30
＋
1
)
=
30
−
1
=
900
−
1
=
899
(2)
2
41
2
2
2
=
(
40
＋
1
)
=
40
＋
2
×
40
×
1
＋
1
=
1600
＋
80
＋
1
=
1681
(3)
21
×
19
2
2
=
(
20
＋
1
)
(
20
−
1
)
=
20
−
1
=
400
−
1
=
399
(4)
2
72
2
2
2
=
(
70
＋
2
)
=
70
＋
2
×
70
×
2
＋
2
=
4900
＋
280
＋
4
=
5184
(5)
2
38
2
2
2
=
(
40
−
2
)
=
40
−
2
×
40
×
2
＋
2
=
1600
−
160
＋
4
=
1444
(6)
2
87
2
2
2
=
(
90
−
3
)
=
90
−
2
×
90
×
3
＋
3
=
8100
−
540
＋
9
=
7569
(7)
32
×
28
2
2
=
(
30
＋
2
)
(
30
−
2
)
=
30
−
2
=
900
−
4
=
896
(8)
49
×
51
2
2
=
(
50
−
1
)
(
50
＋
1
)
=
50
−
1
=
2500
−
1
=
2499
(9)
53
×
47
2
2
=
(
50
＋
3
)
(
50
−
3
)
=
50
−
3
=
2500
−
9
=
2491
(10)
2
62
2
2
2
=
(
60
＋
2
)
=
60
＋
2
×
60
×
2
＋
2
=
3600
＋
240
＋
4
=
3844
(11)
2
88
2
2
2
=
(
90
−
2
)
=
90
−
2
×
90
×
2
＋
2
=
8100
−
360
＋
4
=
7744
(12)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
＋
3
=
900
−
180
＋
9
=
729