解:(1)
+
-
+
,
=(
+
)-(
-
),
=1-
,
=
;
(2)9
+99
+999
+9999
,
=(9+99+999+9999)+(
+
+
+
),
=[(10-1)+(100-1)+(1000-1)+(10000-1)]+(1-
+
-
+
-
+
-
),
=11110-4+1,
=11110-3,
=11107;
(3)4.56×0.27+483×0.0456+1.9×4.56+0.456×30,
=4.56×0.27+4.83×4.56+1.9×4.56+4.56×3,
=4.56×(0.27+4.83+1.9+3),
=4.56×10,
=45.6;
(4)1-
-
-
-
-
-
-
-
,
=1-(
+
+
+
+
+
+
+
),
=1-(1-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
),
=1-(1-
),
=1-1+
,
=
.
分析:(1)運(yùn)用加法結(jié)合律簡算;
(2)把每個(gè)分?jǐn)?shù)拆成整數(shù)加分?jǐn)?shù)的形式,整數(shù)與整數(shù)相加,分?jǐn)?shù)與分?jǐn)?shù)相加.把每個(gè)整數(shù)拆成整十、整百…減1的形式,把每個(gè)分?jǐn)?shù)拆成兩個(gè)分?jǐn)?shù)相減的形式,通過簡算得出結(jié)果;
(3)根據(jù)數(shù)字特點(diǎn),把數(shù)字經(jīng)過變形,運(yùn)用乘法分配律簡算;
(4)把分?jǐn)?shù)拆成兩個(gè)分?jǐn)?shù)相減的形式,然后通過加減相互抵消的方法,求出結(jié)果.
點(diǎn)評:此題主要考查分?jǐn)?shù)、小數(shù)的四則混合運(yùn)算,仔細(xì)觀察,合理應(yīng)用運(yùn)算定律或運(yùn)算技巧進(jìn)行簡便計(jì)算.