计算下面各题,能简算的要简算.7.28+[3/7]+2.72+[4/7]([3/8]+[1/6])÷[1/24]168.

1个回答

  • 解题思路:(1)运用加法交换律与结合律简算;

    (2)把除法改为乘法,运用乘法分配律简算;

    (3)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;

    (4)运用乘法分配律简算,同时把分数化为小数;

    (5)先算除法,再算加法.

    (1)7.28+[3/7]+2.72+[4/7],

    =(7.28+2.72)+([3/7]+[4/7]),

    =10+1,

    =11;

    (2)([3/8]+[1/6])÷[1/24],

    =([3/8]+[1/6])×24,

    =[3/8]×24+[1/6]×24,

    =9+4,

    =13;

    (4)168.1÷(4.3×2-0.4),

    =168.1÷(8.6-0.4),

    =168.1÷8.2,

    =20.5;

    (5)36×[5/8]+36×0.375,

    =36×([5/8]+0.375),

    =36×(0.625+0.375),

    =36×1,

    =36;

    (6)[3/7]+[6/7]÷[2/3],

    =[3/7]+[6/7]×[3/2],

    =[3/7]+[9/7],

    =[12/7].

    点评:

    本题考点: 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: 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律简便计算.