解:
+(5+7
×3
)×
,
=
+(5+26)×
,
=
+31×
,
=3
;
(2)1.75×0.24+0.76÷
,
=1.75×0.24+0.76×1.75,
=1.75×(0.24+0.76),
=1.75×1,
=1.75;
(3)2012×20.11-201.2×201,
=201.2×201.1-201.2×201,
=201.2×(201.1-201),
=201.2×0.1,
=20.12;
(4)1-
-
-
,
=1-(
+
+
+
),
=1-
,
=
分析:(1)按則運算的順序,先算小括號里的乘,再算小括號里的加,然后算括號外面的乘,最后算括號外面的加;
(2)把0.76÷
變成0.76×1.75,利用乘法的分配律變成1.75×(0.24+0.76)計算簡便;
(3)把2012×20.11變成201.2×201.1,利用乘法的分配律變,201.2×(201.1-201)計算簡便;
(4)把原算是變成1-(
+
+
+
)計算簡便.
點評:考查了運算定律與簡便運算,四則混合運算.注意運算順序和運算法則,靈活運用所學的運算律簡便計算.