解:(1)(28×
+12×175%)÷
,
=(28×
+12×175%)×
,
=28×
×
+12×175%×
,
=
+8,
=26
;
(2)0.35÷0.125÷64÷0.5÷0.25,
=0.35÷(0.125×64×0.5×0.25),
=0.35÷(0.125×8×8×0.5×0.25),
=0.35÷[(0.125×8)×(0.5×0.25×8)],
=0.35÷[1×1],
=0.35÷1,
=0.35;
(3)1.25×98+12
×
+1
,
=1.25×98+12.5×0.1+1.25,
=1.25×98+1.25×1+1.25,
=1.25×(98+1+1),
=1.25×100,
=125;
(4)3
×2345+555÷
+654.3×36,
=3.6×2345+555÷
+6543×3.6,
=3.6×2345+6543×3.6+555÷
,
=3.6×(2345+6543)+555×
,
=3.6×8888+5683.2,
=37680;
(5)
+
-
+
-
+
-
,
=1-
+
+
-
-
+
+
-
-
+
+
-
-
,
=1-
,
=
;
(6)
+
+…
=2008,
x-
+
-
+…+
-
=2008,
x-
=2008,
x=2008,
x÷
=2008÷
,
x=2009.
分析:(1)把除以
化成乘以
,再運(yùn)用乘法分配律進(jìn)行簡算;
(2)運(yùn)用除法的運(yùn)算定律進(jìn)行簡算;
(3)運(yùn)用乘法分配律進(jìn)行簡算;
(4)把654.3×36化成6543×3.6,運(yùn)用乘法分配律進(jìn)行簡算;
(5)把算式
+
-
+
-
+
-
化成1-
+
+
-
-
+
+
-
-
+
+
-
-
進(jìn)行簡算;
(6)把
+
+…
=2008化成x-
+
-
+…+
-
=2008,再解方程即可.
點(diǎn)評:運(yùn)算定律是常用的簡便運(yùn)算的方法,要熟練掌握,靈活運(yùn)用.