解题思路:(1)(2)运用乘法分配律简算;
(3)把除法改为乘法,把百分数化为分数,运用乘法分配律简算;
(4)先计算除法,然后运用减法的性质简算.
(1)25-25×99%
=25×(1-99%)
=25×[1/100]
=[1/4];
(2)24×([1/4]+[5/6]-[7/12])
=24×[1/4]+24×[5/6]-24×[7/12]
=6+20-14
=12;
(3)[4/9]×37.5%+[3/8]÷[9/5]
=[4/9]×[3/8]+[3/8]×[5/9]
=[3/8]×([4/9]+[5/9])
=[3/8]×1
=[3/8];
(4)3-[3/8]÷[7/16]-[1/7]
=3-[3/8]×[16/7]-[1/7]
=3-[6/7]-[1/7]
=3-([6/7]+[1/7])
=3-1
=2.
点评:
本题考点: 整数、分数、小数、百分数四则混合运算.
考点点评: 要想算得快、算得巧,就要仔细注意观察题目中数字构成的特点和规律,运用运算定律或运算技巧,进行简便计算.