Question

细心审题，我能算 2 3 - 1 7 =	7 12 ÷21=	2.4× 1 6 =	3÷30%=	42÷ 14 15 =
15 14 × 7 20 =	10×10%=	3-1 2 3 =	1- 3 5 + 2 5 =	5 8 × 3 4 ÷ 5 8 × 3 4 =

Answer 1

分析：根据分数和百分数加减乘除法的计算方法进行计算．

解答：解：

2 3 - 1 7 = 11 21	7 12 ÷21= 1 36	2.4× 1 6 =0.4	3÷30%=10	42÷ 14 15 =45
15 14 × 7 20 = 3 8	10×10%=1	3-1 2 3 =1 1 3	1- 3 5 + 2 5 = 4 5	5 8 × 3 4 ÷ 5 8 × 3 4 = 9 16

点评：口算时，注意运算符号和数据，然后再进一步计算．