递等式计算.(能巧算的要巧算)(1)(80-4)×125 (2)(29+29+29+49)×250 (3)96×(718

1个回答

  • 解题思路:(1)(4)根据乘法分配律计算;

    (2)求出括号里的和,再把分解成100+36再根据乘法分配律进行计算;

    (3)先求括号里的差,再算乘;

    (5)把124分解成100+20+4再根据乘法分配律进行计算;

    (6)把12分解成3×4,再根据乘法结合律进行计算;

    (7)根据减法的性质,先算中括号里的,最后算乘;

    (8)根据同分母分数加减法的计算方法进行计算;

    (9)从左到右依次计算;

    (10)根据减法的性质进行计算.

    (1)(80-4)×125,

    =80×125-4×125,

    =10000-500,

    =9500;

    (2)(29+29+29+49)×250,

    =136×250,

    =(100+36)×250,

    =100×250+9×4×250,

    =25000+9000,

    =34000;

    (3)96×(718-94),

    =96×624,

    =59904;

    (4)32×88-23×88+88,

    =(32-23+1)×88,

    =10×88,

    =880;

    (5)124×25,

    =(100+20+4)×25,

    =100×25+20×25+4×25,

    =2500+500+100,

    =3100;

    (6)125×12×25,

    =125×3×4×25,

    =(125×3)×(4×25),

    =375×100,

    =37500;

    (7)[332-(32+278)]×186,

    =(332-32-278)×186,

    =22×186,

    =4092;

    (8)

    2

    9+

    3

    9+

    4

    9=1;

    (9)

    17

    26+

    9

    26-

    3

    8,

    =1-

    3

    8,

    =

    5

    8;

    (10)1-

    5

    7-

    2

    7,

    =1-((

    5

    7+

    2

    7),

    =1-1,

    =0.

    点评:

    本题考点: 整数四则混合运算;运算定律与简便运算;分数的加法和减法.

    考点点评: 本题综全考查了学生的计算能力,在计算中要灵活运用简便算法.