[文字サイズの変更]
▼
▲
©2024 数学クラブ http://sugaku.club/
月 日( )
● 次の計算をしなさい
[1C1-00]
(1)
91
×
89
(2)
67
×
73
(3)
2
61
(4)
39
×
41
(5)
62
×
58
(6)
2
78
(7)
2
53
(8)
58
×
62
(9)
29
×
31
(10)
91
×
89
(11)
2
53
(12)
47
×
53
©2024 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
91
×
89
2
2
=
(
90
+
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(2)
67
×
73
2
2
=
(
70
−
3
)
(
70
+
3
)
=
70
−
3
=
4900
−
9
=
4891
(3)
2
61
2
2
2
=
(
60
+
1
)
=
60
+
2
×
60
×
1
+
1
=
3600
+
120
+
1
=
3721
(4)
39
×
41
2
2
=
(
40
−
1
)
(
40
+
1
)
=
40
−
1
=
1600
−
1
=
1599
(5)
62
×
58
2
2
=
(
60
+
2
)
(
60
−
2
)
=
60
−
2
=
3600
−
4
=
3596
(6)
2
78
2
2
2
=
(
80
−
2
)
=
80
−
2
×
80
×
2
+
2
=
6400
−
320
+
4
=
6084
(7)
2
53
2
2
2
=
(
50
+
3
)
=
50
+
2
×
50
×
3
+
3
=
2500
+
300
+
9
=
2809
(8)
58
×
62
2
2
=
(
60
−
2
)
(
60
+
2
)
=
60
−
2
=
3600
−
4
=
3596
(9)
29
×
31
2
2
=
(
30
−
1
)
(
30
+
1
)
=
30
−
1
=
900
−
1
=
899
(10)
91
×
89
2
2
=
(
90
+
1
)
(
90
−
1
)
=
90
−
1
=
8100
−
1
=
8099
(11)
2
53
2
2
2
=
(
50
+
3
)
=
50
+
2
×
50
×
3
+
3
=
2500
+
300
+
9
=
2809
(12)
47
×
53
2
2
=
(
50
−
3
)
(
50
+
3
)
=
50
−
3
=
2500
−
9
=
2491