62.8×19-8×62 -62![]() | 3.64×[1÷(2 -2.09)] |
| 1800-1350÷18×6 | (2 +1 +2 +3.375)×![]() |
| 1.9-1.9×(1.9-1.9) | (1-1%×70)÷ . |
-
,=62.8×(19-8-1),
=62.8×10,
=628;
(2)3.64×[1÷(2
-2.09)],=3.64×[1÷0.01],
=3.64×100,
=364;
(3)1800-1350÷18×6,
=1800-75×6,
=1800-450,
=1350;
(4)(

+3.375)×
,=(5+5)×
,=
;(5)1.9-1.9×(1.9-1.9),
=1.9-0,
=1.9;
(6)(1-1%×70)
,=(1-
)×
,=
.分析:(1)用乘法分配律简算;
(2)先算小括号里的减法,再算中括号里的除法,最后算括号外面的乘法;
(3)先算除法,再算乘法,最后算减法;
(4)括号里用加法交换、结合律算出得数,再算括号外的乘法;
(5)先算小括号里的,再算乘法,最后算减法;
(6)先算括号里的乘法,再算括号里的减法,最后算除法.
点评:此题考查整数、分数、小数的四则混合运算,能简算的要简算.
-62
+1
+2
+3.375)×
.