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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)
99
×
101
(2)
2
28
(3)
2
63
(4)
83
×
77
(5)
2
79
(6)
2
69
(7)
2
51
(8)
41
×
39
(9)
99
×
101
(10)
2
33
(11)
68
×
72
(12)
2
33
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
99
×
101
2
2
=
(
100
−
1
)
(
100
＋
1
)
=
100
−
1
=
10000
−
1
=
9999
(2)
2
28
2
2
2
=
(
30
−
2
)
=
30
−
2
×
30
×
2
＋
2
=
900
−
120
＋
4
=
784
(3)
2
63
2
2
2
=
(
60
＋
3
)
=
60
＋
2
×
60
×
3
＋
3
=
3600
＋
360
＋
9
=
3969
(4)
83
×
77
2
2
=
(
80
＋
3
)
(
80
−
3
)
=
80
−
3
=
6400
−
9
=
6391
(5)
2
79
2
2
2
=
(
80
−
1
)
=
80
−
2
×
80
×
1
＋
1
=
6400
−
160
＋
1
=
6241
(6)
2
69
2
2
2
=
(
70
−
1
)
=
70
−
2
×
70
×
1
＋
1
=
4900
−
140
＋
1
=
4761
(7)
2
51
2
2
2
=
(
50
＋
1
)
=
50
＋
2
×
50
×
1
＋
1
=
2500
＋
100
＋
1
=
2601
(8)
41
×
39
2
2
=
(
40
＋
1
)
(
40
−
1
)
=
40
−
1
=
1600
−
1
=
1599
(9)
99
×
101
2
2
=
(
100
−
1
)
(
100
＋
1
)
=
100
−
1
=
10000
−
1
=
9999
(10)
2
33
2
2
2
=
(
30
＋
3
)
=
30
＋
2
×
30
×
3
＋
3
=
900
＋
180
＋
9
=
1089
(11)
68
×
72
2
2
=
(
70
−
2
)
(
70
＋
2
)
=
70
−
2
=
4900
−
4
=
4896
(12)
2
33
2
2
2
=
(
30
＋
3
)
=
30
＋
2
×
30
×
3
＋
3
=
900
＋
180
＋
9
=
1089