脱式计算,能简算的要简算.(1)(25-0.2)÷(1÷0.25)(2)1.5×[4+15.6÷(1.65-0.35)]

1个回答

  • 解题思路:(1)两个括号同时计算.再算括号外的除法;

    (2)先算小括号内的,再算中括号内的除法,然后算中括号内的加法,最后算括号外的乘法;

    (3)先求出算乘法,运用减法的性质简算;

    (4)先算6÷5,原式变为1.2×6.08+3.92×1.2,运用乘法分配律简算.

    (1)(25-0.2)÷(1÷0.25),

    =24.8÷4,

    =6.2;

    (2)1.5×[4+15.6÷(1.65-0.35)],

    =1.5×[4+15.6÷1.3],

    =1.5×[4+12],

    =1.5×16,

    =24;

    (3)90.45-32.44-6.89×4,

    =90.45-32.44-27.56,

    =90.45-(32.44+27.56),

    =90.45-60,

    =30.45;

    (4)1.2×6.08+3.92×(6÷5),

    =1.2×6.08+3.92×1.2,

    =1.2×(6.08+3.92),

    =1.2×10,

    =12.

    点评:

    本题考点: 小数四则混合运算;运算定律与简便运算.

    考点点评: 考查了小数的四则混合运算,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.