脱式计算,能简算的简算. 4.2-1.38+5.8-3.62 1/6÷[1÷(3/5-3/10)] 2÷2/3-2/3÷2 3/5×99+3/5.

问题描述:

脱式计算,能简算的简算.

4.2-1.38+5.8-3.62      
1
6
÷[1÷(
3
5
-
3
10
)]
2
3
-
2
3
÷2     
3
5
×99+
3
5

(1)4.2-1.38+5.8-3.62 
=(4.2+5.8)-(1.38+3.62),
=10-5,
=5;
(2)

1
6
÷[1÷(
3
5
-
3
10
)]
=
1
6
÷[1÷
3
10
],
=
1
6
÷
10
3

=
1
20

(3)2÷
2
3
-
2
3
÷2  
=3-
1
3

=2
2
3

(4)
3
5
×99+
3
5

=(99+1)×
3
5

=100×
3
5

=60.