3.一根彩带，用去它的$\frac{4}{5}$，还剩下$\frac{4}{5}$m。用去的长度与剩下的长度相比较，()。

A.用去的长
B.剩下的长
C.同样长
D.无法比较

3.A

1.直接写出得数。
2.3×4 =
3.6×0.3 =
1.2÷0.3 =
6.1×8 =
4 - 0.4 =
2.8÷40 =
0.8×5.5 =
12.5 + 1.25 =
5.7 - 5.7÷5.7 =
1.8÷0.6×0.4 =

2.3×4 = 9.2
3.6×0.3 = 1.08
1.2÷0.3 = 4
6.1×8 = 48.8
4 - 0.4 = 3.6
2.8÷40 = 0.07
0.8×5.5 = 4.4
12.5 + 1.25 = 13.75
5.7 - 5.7÷5.7 = 4.7
1.8÷0.6×0.4 = 1.2

2.计算下面各题,能简算的要简算。
23.4÷7.8 +2.2
2.5×(4+0.4)
0.35×99 +0.35
63÷0.45÷20
12.95 -3.05÷0.61×0.3
4.25×3.7 +6.3×4.25

23.4÷7.8 + 2.2
= 3 + 2.2
= 5.2
2.5×(4 + 0.4)
= 2.5×4 + 2.5×0.4
= 10 + 1
= 11
0.35×99 + 0.35
= 0.35×(99 + 1)
= 0.35×100
= 35
63÷0.45÷20
= 63÷(0.45×20)
= 63÷9
= 7
12.95 - 3.05÷0.61×0.3
= 12.95 - 5×0.3
= 12.95 - 1.5
= 11.45
4.25×3.7 + 6.3×4.25
= 4.25×(3.7 + 6.3)
= 4.25×10
= 42.5

四、解决问题。
1.陶瓷烧制技艺是国家级非物质文化遗产之一。质检员对两批同样的陶瓷产品进行检测，第一批抽查200个，检测合格175个；第二批抽查300个，检测合格270个。哪一批陶瓷产品的合格情况好些？

1. $175 ÷ 200 = \frac{175}{200} = \frac{7}{8}$
$270 ÷ 300 = \frac{270}{300} = \frac{9}{10}$ $\frac{7}{8} ＜ \frac{9}{10}$
第二批陶瓷产品合格情况好些