考點(diǎn):分?jǐn)?shù)的四則混合運(yùn)算,運(yùn)算定律與簡便運(yùn)算,小數(shù)四則混合運(yùn)算
專題:運(yùn)算順序及法則,運(yùn)算定律及簡算
分析:(1)根據(jù)乘法分配律進(jìn)行簡算;
(2)根據(jù)乘法交換律進(jìn)行簡算;
(3)按照從左向右的順序進(jìn)行計(jì)算;
(4)先算除法,再算減法;
(5)根據(jù)減法的性質(zhì)進(jìn)行簡算;
(6)先算加法,再算除法,最后算乘法.
解答:
解:(1)12×(
+
-
)
=12×
+12×
-12×
=2+3-4
=5-4
=1;
(2)4×27%×2.5
=4×2.5×27%
=10×27%
=2.7;
(3)1-
-
-
-
=
-
-
-
=
-
-
=
-
=
;
(4)6÷
-
÷6
=18-
=17
;
(5)18.15-(3.5-1.75)
=18.15-3.5+1.75
=18.15+1.75-3.5
=19.9-3.5
=16.4;
(6)5×[(
+
)÷
]
=5×[
÷
]
=5×
=8.
點(diǎn)評:考查了運(yùn)算定律與簡便運(yùn)算,四則混合運(yùn)算.注意運(yùn)算順序和運(yùn)算法則,靈活運(yùn)用所學(xué)的運(yùn)算定律簡便計(jì)算.