[文字サイズの変更]
▼
▲
©2026 数学クラブ http://sugaku.club/
月 日( )
● 次の計算をしなさい
[1C1-00]
(1)
49
×
51
(2)
82
×
78
(3)
82
×
78
(4)
2
63
(5)
81
×
79
(6)
92
×
88
(7)
29
×
31
(8)
59
×
61
(9)
2
21
(10)
88
×
92
(11)
71
×
69
(12)
2
62
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
49
×
51
2
2
=
(
50
−
1
)
(
50
+
1
)
=
50
−
1
=
2500
−
1
=
2499
(2)
82
×
78
2
2
=
(
80
+
2
)
(
80
−
2
)
=
80
−
2
=
6400
−
4
=
6396
(3)
82
×
78
2
2
=
(
80
+
2
)
(
80
−
2
)
=
80
−
2
=
6400
−
4
=
6396
(4)
2
63
2
2
2
=
(
60
+
3
)
=
60
+
2
×
60
×
3
+
3
=
3600
+
360
+
9
=
3969
(5)
81
×
79
2
2
=
(
80
+
1
)
(
80
−
1
)
=
80
−
1
=
6400
−
1
=
6399
(6)
92
×
88
2
2
=
(
90
+
2
)
(
90
−
2
)
=
90
−
2
=
8100
−
4
=
8096
(7)
29
×
31
2
2
=
(
30
−
1
)
(
30
+
1
)
=
30
−
1
=
900
−
1
=
899
(8)
59
×
61
2
2
=
(
60
−
1
)
(
60
+
1
)
=
60
−
1
=
3600
−
1
=
3599
(9)
2
21
2
2
2
=
(
20
+
1
)
=
20
+
2
×
20
×
1
+
1
=
400
+
40
+
1
=
441
(10)
88
×
92
2
2
=
(
90
−
2
)
(
90
+
2
)
=
90
−
2
=
8100
−
4
=
8096
(11)
71
×
69
2
2
=
(
70
+
1
)
(
70
−
1
)
=
70
−
1
=
4900
−
1
=
4899
(12)
2
62
2
2
2
=
(
60
+
2
)
=
60
+
2
×
60
×
2
+
2
=
3600
+
240
+
4
=
3844