考點(diǎn):分?jǐn)?shù)的巧算
專(zhuān)題:計(jì)算問(wèn)題(巧算速算)
分析:(1)(2)(3)(5)運(yùn)用乘法分配律簡(jiǎn)算.
(4)先把帶分?jǐn)?shù)化成假分?jǐn)?shù),然后通過(guò)約分計(jì)算.
(3)先把分?jǐn)?shù)化成小數(shù),然后變形為:111×0.49+111×0.36+111×0.15,再用乘法的分配律簡(jiǎn)算.
(6)把帶分?jǐn)?shù)拆成“整數(shù)+分?jǐn)?shù)”的形式,然后整數(shù)加整數(shù),分?jǐn)?shù)加分?jǐn)?shù),分?jǐn)?shù)部分再進(jìn)行分?jǐn)?shù)拆分,進(jìn)行簡(jiǎn)算.
解答:
解:(1)(
+
)×13×17
=
×13×17+
×13×17
=65+68
=133
(2)24×
+51×
=24×
+
×19
=(24+19)×
=43×
=51
(3)777×
+444×0.09+333×0.05
=777×0.07+444×0.09+333×0.05
=111×0.49+111×0.36+111×0.15
=111×(0.49+0.36+0.15)
=111×1
=111
(4)2008÷2008
=2008÷
=2008×
=
(5)
×5.4+0.37×
+9.1÷
=
×5.4+3.7×
+9.1×
=
×(5.4+3.7)+9.1×
=
×9.1+9.1×
=(
+
)×9.1
=1×9.1
=9.1
(6)1
+3
+5
+7
+9
=(1+3+5+7+9)+(
+
+
+
+
)
=25+
×(1-
+
-
+
-
+
-
+
-
)
=25+
×(1-
)
=25+
×
=25+
=25
點(diǎn)評(píng):完成本題要注意分析式中數(shù)據(jù),適當(dāng)?shù)陌褦?shù)據(jù)變形,運(yùn)用合適的簡(jiǎn)便方法計(jì)算.