问题 解答题
脱式计算,写出主要计算过程,能用简便算法的要用简便算法.
①12×
3
8
÷
3
4
4
9
+
5
9
×9
③14÷(
1
3
+
5
6
)×
3
4
④3.6-2.8+16.4-7.2⑤77×
4
5
+23×0.8.
答案

①12×

3
8
÷
3
4

=12×

3
8
×
4
3

=6;

4
9
+
5
9
×9

=

4
9
+5

=5

4
9

③14÷(

1
3
+
5
6
)×
3
4

=14÷

7
6
×
3
4

=14×

6
7
×
3
4

=9;

④3.6-2.8+16.4-7.2

=(3.6+16.4)-(2.8+7.2)

=20-10

=10;

⑤77×

4
5
+23×0.8

=(77+23)×0.8

=100×0.8

=80.

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