(2013•东莞模拟)正确、合理、灵活的计算下面各题.

1个回答

  • 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.