解题思路:(1)括号内运用乘法分配律简算,然后再算括号外的;
(2)括号内进行通分计算,然后再算括号外的,把除法改为乘法计算;
(3)运用除法的性质简算;
(4)根据数字特点,把原式变为1.28×2.37-0.28×2.37,运用乘法分配律简算;
(5)把百分数和分数转化为小数0.65,运用乘法分配律简算.
(1)([3/4]-[3/4]×[2/5])÷[1/5],
=[(1-[2/5])×[3/4]]×5,
=[3/5]×[3/4]×5,
=[9/4];
(2)([2/3]-[1/2]+[1/6])÷[1/24],
=[1/3]×24,
=8;
(3)7.28÷0.8÷12.5,
=7.28÷(0.8×12.5),
=7.28÷10,
=0.728;
(4)1.28×2.37-2.8×0.237,
=1.28×2.37-0.28×2.37,
=(1.28-0.28)×2.37,
=1×2.37,
=2.37;
(5)0.65×14+87×65%-[13/20],
=0.65×14+87×0.65-0.65,
=0.65×(14+87-1),
=0.65×100,
=65.
点评:
本题考点: 分数的四则混合运算;运算定律与简便运算;小数四则混合运算.
考点点评: 考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.