Question

口算

0.67+0.3=	12×0.5=	3.2+1.8=	0.8×25-10=	5 4 -1=	1 7 + 1 5 =	1- 3 4 =
3 5 + 1 6 + 5 6 =	1 2 - 1 7 =	1- 4 5 =	1 2 - 1 7 =	1 6 + 2 5 =	7×1.3+7×6.7=	0.87-0.5=
2- 1 3 =	3 4 - 1 2 =	1 4 - 1 7 =	3 4 + 1 4 =	1.4- 2 5 =	1÷0.25=	11 14 + 9 14 =

Answer 1

考点：分数的加法和减法,小数四则混合运算

专题：运算顺序及法则

分析：根据小数和分数加减乘除法的计算方法进行计算．

3

5

+

1

6

+

5

6

根据加法结合律进行简算；
7×1.3+7×6.7根据乘法分配律进行简算．

解答： 解：

0.67+0.3=0.97	12×0.5=6	3.2+1.8=5	0.8×25-10=10	5 4 -1= 1 4	1 7 + 1 5 = 12 35	1- 3 4 = 1 4
3 5 + 1 6 + 5 6 =1 3 5	1 2 - 1 7 = 5 14	1- 4 5 = 1 5	1 2 - 1 7 = 5 14	1 6 + 2 5 = 17 30	7×1.3+7×6.7=56	0.87-0.5=0.35
2- 1 3 =1 2 3	3 4 - 1 2 = 1 4	1 4 - 1 7 = 3 28	3 4 + 1 4 =1	1.4- 2 5 =1	1÷0.25=4	11 14 + 9 14 = 10 7

点评：口算时，注意运算符号和数据，然后再进一步计算．