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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)
83
×
77
(3)
41
×
39
(4)
68
×
72
(5)
37
×
43
(6)
19
×
21
(7)
63
×
57
(8)
2
43
(9)
59
×
61
(10)
63
×
57
(11)
63
×
57
(12)
101
×
99
©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)
83
×
77
2
2
=
(
80
＋
3
)
(
80
−
3
)
=
80
−
3
=
6400
−
9
=
6391
(3)
41
×
39
2
2
=
(
40
＋
1
)
(
40
−
1
)
=
40
−
1
=
1600
−
1
=
1599
(4)
68
×
72
2
2
=
(
70
−
2
)
(
70
＋
2
)
=
70
−
2
=
4900
−
4
=
4896
(5)
37
×
43
2
2
=
(
40
−
3
)
(
40
＋
3
)
=
40
−
3
=
1600
−
9
=
1591
(6)
19
×
21
2
2
=
(
20
−
1
)
(
20
＋
1
)
=
20
−
1
=
400
−
1
=
399
(7)
63
×
57
2
2
=
(
60
＋
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591
(8)
2
43
2
2
2
=
(
40
＋
3
)
=
40
＋
2
×
40
×
3
＋
3
=
1600
＋
240
＋
9
=
1849
(9)
59
×
61
2
2
=
(
60
−
1
)
(
60
＋
1
)
=
60
−
1
=
3600
−
1
=
3599
(10)
63
×
57
2
2
=
(
60
＋
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591
(11)
63
×
57
2
2
=
(
60
＋
3
)
(
60
−
3
)
=
60
−
3
=
3600
−
9
=
3591
(12)
101
×
99
2
2
=
(
100
＋
1
)
(
100
−
1
)
=
100
−
1
=
10000
−
1
=
9999