(2012•哈尔滨模拟) 脱式计算,能简算的要简算:
1个回答

解题思路:(1)依据减法的性质化原式为:4.67-2.98-0.67,再依据加法的结合律解答,

(2)依据减法性质解答,

(3)运用乘法交换律和结合律解答,

(4)(5)(6)运用乘法分配律解答.

(1)4.67-(2.98+0.67),

=4.67-0.67-2.98,

=4-2.98,

=1.02;

(2)[8/49]÷[[9/8]-([1/8]+[3/7])],

=[8/49]÷[[9/8]−

1

8−

3

7],

=[8/49]÷[1-[3/7]]

=[8/49]÷[4/7],

=[2/7];

(3)8×0.4×12.5×2.5,

=(8×12.5)×(0.4×2.5),

=100×1,

=100;

(4)125×(8+0.8+0.08),

=125×8+125×0.8+125×0.08,

=1000+100+10,

=1110;

(5)1.89×0.9+0.189,

=1.89×0.9+1.89×0.1,

=1.89×(0.9+0.1),

=1.89×1,

=1.89;

(6)23.8×99+2.38,

=23.8×(100-1)+2.38,

=23.8×100-23.8×1+2.38,

=2380-23.8+2.38,

=2356.2+2.38,

=2358.58.

点评:

本题考点: 小数四则混合运算;运算定律与简便运算;分数的四则混合运算.

考点点评: 本题主要考查学生运用四则运算计算,以及运用定律和性质简算的能力.