39.5+2.70+6.30简便运算如下:39.5+2.7+6.3=39.5+(2.7+6.3)=39.5+9=48.5这个简便运算运用了加法的交换律定律。
简便计算39.5+2.70+6.30=39.5+(2.7+6.3)=39.5+9=48.5