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©2019 数学クラブ http://sugaku.club/
月 日（ ）
● 次の計算をしなさい
[1C1-00]
(1)
83
×
77
(2)
52
×
48
(3)
49
×
51
(4)
59
×
61
(5)
19
×
21
(6)
39
×
41
(7)
2
27
(8)
42
×
38
(9)
47
×
53
(10)
42
×
38
(11)
92
×
88
(12)
2
43
©2019 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
83
×
77
2
2
=
(
80
＋
3
)
(
80
−
3
)
=
80
−
3
=
6400
−
9
=
6391
(2)
52
×
48
2
2
=
(
50
＋
2
)
(
50
−
2
)
=
50
−
2
=
2500
−
4
=
2496
(3)
49
×
51
2
2
=
(
50
−
1
)
(
50
＋
1
)
=
50
−
1
=
2500
−
1
=
2499
(4)
59
×
61
2
2
=
(
60
−
1
)
(
60
＋
1
)
=
60
−
1
=
3600
−
1
=
3599
(5)
19
×
21
2
2
=
(
20
−
1
)
(
20
＋
1
)
=
20
−
1
=
400
−
1
=
399
(6)
39
×
41
2
2
=
(
40
−
1
)
(
40
＋
1
)
=
40
−
1
=
1600
−
1
=
1599
(7)
2
27
2
2
2
=
(
30
−
3
)
=
30
−
2
×
30
×
3
＋
3
=
900
−
180
＋
9
=
729
(8)
42
×
38
2
2
=
(
40
＋
2
)
(
40
−
2
)
=
40
−
2
=
1600
−
4
=
1596
(9)
47
×
53
2
2
=
(
50
−
3
)
(
50
＋
3
)
=
50
−
3
=
2500
−
9
=
2491
(10)
42
×
38
2
2
=
(
40
＋
2
)
(
40
−
2
)
=
40
−
2
=
1600
−
4
=
1596
(11)
92
×
88
2
2
=
(
90
＋
2
)
(
90
−
2
)
=
90
−
2
=
8100
−
4
=
8096
(12)
2
43
2
2
2
=
(
40
＋
3
)
=
40
＋
2
×
40
×
3
＋
3
=
1600
＋
240
＋
9
=
1849