(2011•慈溪市模拟)递等式计算:

1个回答

  • 解题思路:(1)先算乘法再算除法,最后算减法;

    (2)运用加法结合律简算;

    (3)先把222×999变成666×333,然后再运用乘法分配律简算;

    (4)先把小括号去掉(注意括号外是减法,里面的运算符合要改变),然后计算中括号里面的,最后算括号外的除法;

    (5)[3/1×4]=1

    1

    4

    [3/4×7]=[1/4]

    1

    7

    [3/7×10]=[1/7]-[1/10]…;

    有以上规律化简求解;

    (6)先把(289+[5/6]+[7/8]+[7/10])÷([5/6]+[7/8]+[7/10])分成289÷([5/6]+[7/8]+[7/10])+([5/6]+[7/8]+[7/10])÷([5/6]+[7/8]+[7/10]),然后在根据商不变规律简算.

    (1)2000-72×625÷36,

    =2000-45000÷36,

    =2000-1250,

    =750;

    (2)4.8-[4/17]+5.2-[13/17],

    =(4.8+5.2)-([4/17]+[13/17]),

    =10-1,

    =9;

    (3)222×999+333×334,

    =666×333+333×334,

    =(666+334)×333,

    =1000×333,

    =333000;

    (4)[5[3/20]-(4.15-2[1/3])]÷3[1/3],

    =[5[3/20]-4[3/20]+2[1/3]]÷3[1/3],

    =[1+2[1/3]]÷3[1/3],

    =3[1/3]÷3[1/3],

    =1;

    (5)[3/1×4]+[3/4×7]+[3/7×10]+…+[3/91×94],

    =1-[1/4]+[1/4]−

    1

    7+[1/7]-[1/10]+…+[1/91]-[1/94],

    =1-[1/94],

    =[93/94];

    (6)(289+[5/6]+

    点评:

    本题考点: 整数、分数、小数、百分数四则混合运算;运算定律与简便运算;分数的巧算.

    考点点评: 本题考查了较复杂的简便运算,注意找清楚规律,再根据规律化简.