計(jì)算(能簡(jiǎn)算的要簡(jiǎn)算)
99×8.4+0.84
(37.62+20.76)÷0.042
4.8×6.2÷12.4
3.75÷[0.03×(1.34-0.84)].
解:(1)99×8.4+0.84
=990×0.84+0.84×1,
=(990+1)×0.84,
=991×0.84,
=832.44;
(2)(37.62+20.76)÷0.042
=58.38÷0.042,
=843÷0.6,
=1390;
(3)4.8×6.2÷12.4
=29.76÷12.4,
=2.4;
(4)3.75÷[0.03×(1.34-0.84)]
=3.75÷[0.03×0.5],
=3.75÷0.015,
=250.
分析:(1)依據(jù)積不變的規(guī)律,將算式中的99擴(kuò)大10倍,8.4縮小10倍,將0.84改寫(xiě)成0.84×1,然后再利用乘法分配律進(jìn)行計(jì)算即可;
(2)、(3)、(4)按照小數(shù)的四則混合運(yùn)算進(jìn)行計(jì)算即可得到答案;
點(diǎn)評(píng):此題主要考查的是小數(shù)的四則混合運(yùn)算和乘法分配律的使用.