解:(1)
÷13+
×
,
=
,
=(
)×
,
=1×
,
=
;
(2)54.2-
+4.8-
,
=54.2+4.8-(
),
=59-2,
=57;
(3)3.5×
+5.5×80%+0.8,
=(3.5+5.5+1)×0.8,
=10×0.8,
=8;
(4)56×99,
=56×(100-1),
=56×100-56,
=5600-56,
=5544.
分析:(1)
÷13+
×
,把除數(shù)轉(zhuǎn)化為乘它的倒數(shù),再運(yùn)用乘法分配律進(jìn)行簡(jiǎn)算;
(2)54.2-
+4.8-
,運(yùn)用加法結(jié)合律和減法的運(yùn)算性質(zhì)進(jìn)行簡(jiǎn)算;
(3)3.5×
+5.5×80%+0.8,把
和80%化成0.8,再運(yùn)用乘法分配律進(jìn)行簡(jiǎn)算;
(4)56×99,轉(zhuǎn)化為56×(100-1),再運(yùn)用乘法分配律進(jìn)行簡(jiǎn)算.
點(diǎn)評(píng):此題主要考查運(yùn)用運(yùn)算定律和運(yùn)算性質(zhì)進(jìn)行小數(shù)、分?jǐn)?shù)四則混合運(yùn)算的簡(jiǎn)便計(jì)算.