【题目】
计算下面各题(能简算的要简算)
48-2.3×12
50×(0.8+0.4)
7.34×2.1+7.34×7.8+7.34×1.1
20.5÷1.25÷0.8
(8.1-5.4)÷3.6+85.7
9.88×9+9.88.
分析:①、⑤按小数四则混合运算的运算顺序:先算乘除,后算加减,有括号的先算括号的;进行解答;
②、③、⑥运用运用乘法分配律进行简算;
④根据除法的性质进行简算.解答:解:①48-2.3×12,
=48-27.6,
=20.4;
②50×(0.8+0.4),
=50×0.8+50×0.4,
=40+20,
=60;
③7.34×2.1+7.34×7.8+7.34×1.1,
=7.34×(2.1+7.8+1.1),
=7.34×10,
=73.4;
④20.5÷1.25÷0.8,
=20.5÷(1.25×0.8),
=20.5÷1,
=20.5;
⑤(8.1-5.4)÷3.6+85.7,
=2.7÷3.6+85.7,
=0.75+85.7,
=86.45;
⑥9.88×9+9.88,
=9.88×(9+1),
=9.88×10,
=98.8.点评:此题考查了小数四则混合运算,灵活掌握乘法运算定律,是解答此题的关键.