奇思妙算(用简便方法计算下面各题)(1) 7 8 × 5 6 × 8 7 - 1

2025-06-27 20:10:13
推荐回答(1个)
回答1:

(1)
7
8
×
5
6
×
8
7
-
1
3

=(
7
8
×
8
7
)×
5
6
-
1
3

=1×
5
6
-
1
3

=
5
6
-
1
3

=
1
2


(2)
7
9
÷2
1
5
+
2
9
×
5
11

=
7
9
×
5
11
+
2
9
×
5
11

=(
7
9
+
2
9
)×
5
11

=1×
5
11

=
5
11


(3))(
2
9
×13-
2
9
)÷
1
3

=(13-1)×
2
9
×3
=12×
2
9
×3
=8