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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)
72
×
68
(2)
2
49
(3)
98
×
102
(4)
81
×
79
(5)
2
31
(6)
41
×
39
(7)
2
52
(8)
2
42
(9)
78
×
82
(10)
77
×
83
(11)
2
48
(12)
2
53
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
72
×
68
2
2
=
(
70
＋
2
)
(
70
−
2
)
=
70
−
2
=
4900
−
4
=
4896
(2)
2
49
2
2
2
=
(
50
−
1
)
=
50
−
2
×
50
×
1
＋
1
=
2500
−
100
＋
1
=
2401
(3)
98
×
102
2
2
=
(
100
−
2
)
(
100
＋
2
)
=
100
−
2
=
10000
−
4
=
9996
(4)
81
×
79
2
2
=
(
80
＋
1
)
(
80
−
1
)
=
80
−
1
=
6400
−
1
=
6399
(5)
2
31
2
2
2
=
(
30
＋
1
)
=
30
＋
2
×
30
×
1
＋
1
=
900
＋
60
＋
1
=
961
(6)
41
×
39
2
2
=
(
40
＋
1
)
(
40
−
1
)
=
40
−
1
=
1600
−
1
=
1599
(7)
2
52
2
2
2
=
(
50
＋
2
)
=
50
＋
2
×
50
×
2
＋
2
=
2500
＋
200
＋
4
=
2704
(8)
2
42
2
2
2
=
(
40
＋
2
)
=
40
＋
2
×
40
×
2
＋
2
=
1600
＋
160
＋
4
=
1764
(9)
78
×
82
2
2
=
(
80
−
2
)
(
80
＋
2
)
=
80
−
2
=
6400
−
4
=
6396
(10)
77
×
83
2
2
=
(
80
−
3
)
(
80
＋
3
)
=
80
−
3
=
6400
−
9
=
6391
(11)
2
48
2
2
2
=
(
50
−
2
)
=
50
−
2
×
50
×
2
＋
2
=
2500
−
200
＋
4
=
2304
(12)
2
53
2
2
2
=
(
50
＋
3
)
=
50
＋
2
×
50
×
3
＋
3
=
2500
＋
300
＋
9
=
2809