计算下面各题,能用简便方法的要用简便方法计算

1个回答

  • 解题思路:(1)先把2.4分解成0.6×4,再运用乘法结合律简算;

    (2)先把1.2分解成(1+0.2)再运用乘法分配律简算;

    (3)先把10.1分解成(10.1+1),再运用乘法分配律简算;

    (4)先把8.8分解成1.1×8,再运用乘法结合律简算;

    (5)(6)运用乘法分配律简算;

    (7)先乘法,再算减法;

    (8)先算乘法,再算加法;

    (9)根据加法交换律简算;

    (10)运用乘法分配律简算;

    (11)先算小括号里面的减法,再算括号外的乘法;

    (12)先算乘法,再算减法.

    (1)2.4×2.5

    =0.6×4×2.5

    =0.6×(4×2.5)

    =0.6×10

    =6;

    (2)9.8×1.2

    =9.8×(1+0.2)

    =9.8×1+9.8×0.2

    =9.8+1.96

    =11.76;

    (3)10.1×3.4

    =(10+0.1)×3.4

    =10×3.4+0.1×3.4

    =34+0.34

    =34.34;

    (4)8.8×12.5

    =(1.1×8)×12.5

    =1.1×(8×12.5)

    =1.1×100

    =110;

    (5)(2.5-0.25)×4

    =2.5×4-0.25×4

    =10-1

    =9;

    (6)3.6×5.2+4.8×3.6

    =(5.2+4.8)×3.6

    =10×3.6

    =36;

    (7)50.4×1.9-1.8

    =95.76-1.8

    =93.96;

    (8)25.8+3.75×0.24

    =25.8+0.9

    =26.7;

    (9)54.7-29.8+5.3

    =54.7+5.3-29.8

    =60-29.8

    =30.2;

    (10)11×5.7-5.7

    =(11-1)×5.7

    =10×5.7

    =57;

    (11)(12.3-8.05)×0.4

    =4.25×0.4

    =1.7;

    (12)7.06×2.4-5.7

    =16.944-5.7

    =11.244.

    点评:

    本题考点: 小数四则混合运算;运算定律与简便运算.

    考点点评: 此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.