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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)
18
×
22
(2)
22
×
18
(3)
2
49
(4)
17
×
23
(5)
2
29
(6)
89
×
91
(7)
21
×
19
(8)
72
×
68
(9)
23
×
17
(10)
2
58
(11)
2
43
(12)
2
42
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
18
×
22
2
2
=
(
20
−
2
)
(
20
＋
2
)
=
20
−
2
=
400
−
4
=
396
(2)
22
×
18
2
2
=
(
20
＋
2
)
(
20
−
2
)
=
20
−
2
=
400
−
4
=
396
(3)
2
49
2
2
2
=
(
50
−
1
)
=
50
−
2
×
50
×
1
＋
1
=
2500
−
100
＋
1
=
2401
(4)
17
×
23
2
2
=
(
20
−
3
)
(
20
＋
3
)
=
20
−
3
=
400
−
9
=
391
(5)
2
29
2
2
2
=
(
30
−
1
)
=
30
−
2
×
30
×
1
＋
1
=
900
−
60
＋
1
=
841
(6)
89
×
91
2
2
=
(
90
−
1
)
(
90
＋
1
)
=
90
−
1
=
8100
−
1
=
8099
(7)
21
×
19
2
2
=
(
20
＋
1
)
(
20
−
1
)
=
20
−
1
=
400
−
1
=
399
(8)
72
×
68
2
2
=
(
70
＋
2
)
(
70
−
2
)
=
70
−
2
=
4900
−
4
=
4896
(9)
23
×
17
2
2
=
(
20
＋
3
)
(
20
−
3
)
=
20
−
3
=
400
−
9
=
391
(10)
2
58
2
2
2
=
(
60
−
2
)
=
60
−
2
×
60
×
2
＋
2
=
3600
−
240
＋
4
=
3364
(11)
2
43
2
2
2
=
(
40
＋
3
)
=
40
＋
2
×
40
×
3
＋
3
=
1600
＋
240
＋
9
=
1849
(12)
2
42
2
2
2
=
(
40
＋
2
)
=
40
＋
2
×
40
×
2
＋
2
=
1600
＋
160
＋
4
=
1764