| 900-199= | 237+163= | + = | 2- = | 3+0.3= |
| 0.39×10= | 8.4÷4.2= | 0.32= | 25×4÷5= | 1- + = |
| 900-199=701, | 237+163=400, | + = , | 2- =1 , | 3+0.3=3.3, |
| 0.39×10=3.9, | 8.4÷4.2=2, | 0.32=0.09, | 25×4÷5=20, | 1- + = . |
分析:900-199根据凑整法简算;
0.32=0.3×0.3,由此求解;
25×4÷5,1-
+
按照从左到右的顺序计算.其它题目根据运算法则直接求解.
点评:口算题目要求快速准确,能运用简算方法的要简算.
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