用简便方法计算(1)0.9999×0.7+0.1111×2.7;(2)(1+0.228-0.21)×(0.228-0.2

1个回答

  • 解题思路:(1)把0.9999拆成0.1111×9,然后再根据乘法分配律进行简算即可.

    (2)设1+0.228-0.21=a,0.228-0.21=b,通过代入,即可求出问题的答案.

    (1)0.9999×0.7+0.1111×2.7

    =(0.1111×9)×0.7+0.1111×2.7

    =0.1111×6.3+0.1111×2.7

    =0.1111×(6.3+2.7)

    =0.1111×9

    =0.9999

    (2)设1+0.228-0.21=a,0.228-0.21=b,

    (1+0.228-0.21)×(0.228-0.21+0.2003)-(1+0.228-0.21+0.2003)×(0.228-0.21)

    =a×(b+0.2003)-(a+0.2003)×b

    =ab+0.2003a-ab-0.2003b

    =0.2003×(a-b)

    =0.2003×1

    =0.2003

    点评:

    本题考点: 小数的巧算.

    考点点评: 完成此题,应仔细观察数据特点,采用巧妙的方法,解决问题.