用简便方法计算.12.6×0.8

1个回答

  • 解题思路:(1)可将12.6变为12.5+0.1后,根据乘法分配律计算.

    (2)可将99.6变为100-0.4后,根据乘法分配律计算.

    (3)可将100.1变为100+0.1后,根据乘法分配律计算.

    (4)可将9.3×17变为93×1.7后,根据乘法分配律计算.

    (5)可将8.8变为8+0.8后,根据乘法分配律计算.

    (6)可根据乘法分配律计算.

    (1)12.6×0.8

    =(12.5+0.1)×0.8

    =12.5×0.8+0.1×0.8

    =10+0.08

    =10.08;

    (2)99.6×2.5

    =(100-0.4)×2.5

    =100×2.5-0.4×2.5

    =250-1

    =248;

    (3)8.7×100.1

    =8.7×(100+0.1)

    =8.7×100+8.7×0.1

    =870+0.87

    =870.87;

    (4)9.3×17+93×8.3

    =93×1.7+93×8.3

    =93×(1.7+8.3 )

    =93×10

    =930;

    (5)12.5×8.8

    =12.5×(8+0.8)

    =12.5×8+12.5×0.8

    =100+10

    =110;

    (6)401×0.25-0.25

    =(401-1)×0.25

    =400×0.25

    =100.

    点评:

    本题考点: 运算定律与简便运算.

    考点点评: 本题考查考查了学生灵活运用乘法分配律对算式进行简便计算的能力.