解题思路:(1)连续减去两个数,就等于减去这两个数的和;
(2)把32拆成8×4,然后再计算即可;
(3)根据乘法分配律进行计算即可;
(4)把99拆成98+1,再根据乘法分配律进行计算即可;
(5)把[1/4]化成0.25,再根据乘法分配律进行计算即可;
(6)80%化成0.8,[4/5]化成0.8,再根据乘法分配律进行计算即可.
(1)57.5-4.25-15.75,
=57.5-(4.25+15.75),
=57.5-20,
=37.5;
(2)125×32,
=125×(8×4),
=125×8×4,
=1000×4,
=4000;
(3)[5/7]×16.31-[5/7]×2.31,
=[5/7]×(16.31-2.31),
=[5/7]×14,
=10;
(4)99×[7/98],
=(98+1)×[7/98],
=98×[7/98]+1×[7/98],
=7+[7/98],
=7[7/98];
(5)0.76×0.25+[1/4]×0.24,
=0.76×0.25+0.25×0.24,
=0.25×(0.76+0.24),
=0.25×1,
=0.25;
(6)[4/13]×0.8+[3/13]×80%+[4/5]×[6/13],
=[4/13]×0.8+[3/13]×0.8+0.8×[6/13],
=([4/13]+[3/13]+[6/13])×0.8,
=1×0.8,
=0.8.
点评:
本题考点: 小数的加法和减法;整数的乘法及应用;运算定律与简便运算;整数、分数、小数、百分数四则混合运算.
考点点评: 根据题意,选择合适的运算定律进行简算即可.