+ = | 20× = | 0.36÷0.6= | - = ÷2= | 3.5-3.05= |
÷ = | 7×( + )= | × = | 1- = | ÷ = |
4- - = | 0.25×12= | × = | 3.27+1.83= | + + = |
+ = , | 20× =12, | 0.36÷0.6=0.6, | - = , ÷2= , | 3.5-3.05=0.45, |
÷ = , | 7×( + )=3 , | × = , | 1- = , | ÷ = , |
4- - =3, | 0.25×12=3, | × = , | 3.27+1.83=5.1, | + + =1 . |
分析:根据分数和小数的加减乘除的计算方法进行计算即可.7×(
+
)可以运用乘法分配律,
+
+
可以运用加法交换和结合律进行简算.点评:进行口算时,注意运算符号和数据,再进行计算,能简算的要简算.
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