脱式计算(能简算的用简便算法).(1)[9.2+0.8×(9-7.75)]÷0.4; (2)3.5×9.8+0.35×2;(3)

2024-11-23 07:25:32
推荐回答(1个)
回答1:

(1)[9.2+0.8×(9-7.75)]÷0.4
=[9.2+0.8×1.25]÷4
=[9.2+1]÷4
=2.55         
 
(2)3.5×9.8+0.35×2
=3.5×(9.8+0.2)
=3.5×10
=35

(3)28×

26
27

=(27+1)×
26
27

=27×
26
27
+
26
27

=26+
26
27

=26
26
27


(4)[(
2
3
-
3
5
)×
15
4
+
2
3
11
12

=[
1
15
×
15
4
+
2
3
11
12

=[
1
4
+
2
3
11
12

=
11
12
×
12
11

=1