计算下面各题,能简算的要简算.(1)8.11+[3/7]+2.89+[4/7]        (2)[2/5]+[1/3

1个回答

  • 解题思路:(1)先变形为(8.11+2.89)+([3/7]+[4/7]),再计算即可求解;

    (2)(3)先算同分母分数,再相加即可求解;

    (4)先通分,再计算即可求解;

    (5)先算小括号里面的加法,再算括号外面的减法.

    (1)8.11+[3/7]+2.89+[4/7]

    =(8.11+2.89)+([3/7]+[4/7])

    =11+1

    =12;

    (2)[2/5]+[1/3]+[3/5]

    =[2/5]+[3/5]+[1/3]

    =1+[1/3]

    =1[1/3];

    (3)[9/7]+[1/8]+[3/8]+[5/7]

    =([9/7]+[5/7])+([1/8]+[3/8])

    =2+[1/2]

    =2[1/2];

    (4)[7/8]-[5/12]+[1/6]

    =[21/24]-[10/24]+[4/24]

    =[5/8];

    (5)[3/5]-(

    点评:

    本题考点: 分数的简便计算.

    考点点评: 此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.