| 直接写得数. 180+470= | 5÷8= | 25×2.4= | 12- = |
÷14= | + = | 1.25× ×0.8= | × = |
÷ = | - = | ×4÷4× = | 2.4× = |
( + )×16= | 12.01×9.98≈ | 2÷0.2%= | 60×20%= |
| 解:180+470=650; | 5÷8=0.625; | 25×2.4=60; | 12- =11 ; |
÷14= ; | + = ; | 1.25× ×0.8= ; | × =0.4; |
÷ =2; | - = ; | ×4÷4× = ; | 2.4× =0.9; |
( + )×16=6; | 12.01×9.98≈120; | 2÷0.2%=1000; | 60×20%=12. |
分析:横向数:(1)(2)依据整数四则运算计算方法解答;
(3)化2.4=4×0.6,再运用乘法结合律解答;
(4)(5)(6)(8)(9)(10)(11)(12)(15)(16)依据分数四则运算计算方法解答;
(7)运用乘法交换律和结合律解答;
(13)运用乘法分配律解答;
(14)把12.01看作12,9.98看作10解答.
点评:本题主要考查学生依据四则运算计算方法解决问题的能力,解答时注意:有简便算法的要正确的选择并应用运算定律进行简便计算.
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