(2012•黄岩区)脱式计算.(能简算的要简算)

1个回答

  • 解题思路:(1)先算除法,再算加法和减法;

    (2)把小数化为分数,再计算;

    (3)运用加法交换律与结合律简算;

    (4)把64看作4×2×8,把百分数化为小数,运用乘法交换律与结合律简算;

    (5)先算小括号内的,再算中括号内的,最后算括号外的;

    (6)把百分数和和分数化为小数,运用乘法分配律简算.

    (1)1020+270÷18-864,

    =1020+15-864,

    =171;

    (2)[2/3÷0.8×

    3

    4],

    =[2/3]÷[4/5]×[3/4],

    =[2/3]×[5/4]×[3/4],

    =[5/8];

    (3)[1/8]+[5/7]+6.875+[2/7],

    =([1/8]+6.875)+([5/7]+[2/7]),

    =(0.125+6.875)+1,

    =7+1,

    =8;

    (4)0.25×64×125%,

    =0.25×4×2×8×1.25,

    =(0.25×4)×(8×1.25)×2,

    =1×10×1,

    =20;

    (5)[[8/15]-([7/12]-[2/5])]×[15/14],

    =[[8/15]-[11/60]]×[15/14],

    =[21/60]×[15/14],

    =[3/8];

    (6)6.35×0.75+4.65×75%-[3/4],

    =6.35×0.75+4.65×0.75-0.75,

    =(6.35+4.65-1)×0.75,

    =10×0.75,

    =7.5.

    点评:

    本题考点: 整数、分数、小数、百分数四则混合运算;整数四则混合运算.

    考点点评: 此题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.