解题思路:算式①③④⑤⑥都是运用乘法的分配律进行计算,使计算更加简便.
算式②运用一个数减去两个数的差,可以用这个数减去被减数加上减数.
①(1.75×0.2+1.75×0.8)÷0.175,
=1.75×(0.2+0.8)÷0.175,
=1.75÷0.175,
=10;
②10[1/4]-(6[1/4]-2[1/5]),
=10.25-6.25+2.2,
=4+2.2,
=6.2;
③243×8[1/4]+75.7×82.5,
=243×8.25+757×8.25,
=8.25×(243+757),
=8.25×1000,
=8250;
④[3/8]×1[1/4]+125%+0.625×1.25,
=0.375×1.25++1.25+0.625×1.25,
=1.25×(0.375+0.625+1),
=1.25×2,
=2.5;
⑤0.91÷[4/5]+1.25×1.09,
=0.91×1.25+1.25×1.09,
=1.25×(0.91+1.09),
=1.25×2,
=2.5;
⑥([5/6]+[7/8]-[5/12])÷[1/24],
=([5/6+
7
8−
5
12])×24,
=24×[5/6]+24×[7/8]-24×[5/12],
=20+21-10,
=31.
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: 本题主要考查了学生能否根据数字的特点,选择运用乘法的分配律进行计算,运用运算定律使计算更加简便.