考點(diǎn):分?jǐn)?shù)的四則混合運(yùn)算
專題:運(yùn)算順序及法則
分析:(1)根據(jù)數(shù)字特點(diǎn),通過數(shù)字變形,運(yùn)用乘法分配律簡算.
(2)根據(jù)除法的運(yùn)算性質(zhì)簡算.
(3)通過觀察,每個(gè)分?jǐn)?shù)的分母中的兩個(gè)因數(shù)相差都是3,因此提出
,然后把每個(gè)分?jǐn)?shù)拆成兩個(gè)分?jǐn)?shù)相減的形式,通過加減相互抵消,解決問題.
解答:
解:(1)(0.34×2400×0.25+3×7
+26.25÷
)÷
=(0.34×2400×0.25+3×7
+26.25×3)÷
=[0.34×600×4×0.25+3×(7.75+26.25)]÷
=(0.34×600+3×34)÷
=(34×6+3×34)×
=(3+6)×34×
=9×34×
=1989
(2)(
×
1×
)÷(
×
×
)
=(
÷
)×(
÷
)×(
÷
)
=2×2×2
=8
(3)
+
+
+
+…+
=
×(
+
+
+
+…+
)
=
×(1-
+
-
+
-
+
-
+…+
-
)
=
×(1-
)
=
×
=
點(diǎn)評(píng):注意觀察題目中數(shù)字構(gòu)成的特點(diǎn)和規(guī)律,善于靈活運(yùn)用運(yùn)算定律或運(yùn)算技巧,巧妙解答.