《2025年口算训练五年级数学上册人教版双色升级版》

答案： ```
12.24
× 0.03
------
0.3672
85.1
× 0.04
------
3.404
0.48
× 0.34
------
0.1632
12.9
× 0.05
------
0.645
47.05
× 0.25
------
11.7625
```

$ 3.5×0.2= $
$ 3.5+0.2= $
$ 3.5-0.2= $
$ 2.56×0.1= $
$ 2.56+0.1= $
$ 2.56-0.1= $
$ 7.7×0.4= $
$ 7.7+0.4= $
$ 7.7-0.4= $
$ 1.5×0.5= $
$ 1.5+0.5= $
$ 1.5-0.5= $
$ 1.53×0= $
$ 1.53+0.07= $
$ 0.36+0.72= $
$ 0.72-0.36= $
$ 0.72×0.01= $
$ 1.6×12.5= $
$ 1.6+12.5= $
$ 1.6-0.125= $
$ 1.6×0.001= $

答案： 解析：
这些题目都是基础的数学运算题目，包括乘法、加法和减法。我们将直接计算每个表达式的结果。
答案：
$3.5 × 0.2 = 0.7$；
$3.5 + 0.2 = 3.7$；
$3.5 - 0.2 = 3.3$；
$2.56 × 0.1 = 0.256$；
$2.56 + 0.1 = 2.66$；
$2.56 - 0.1 = 2.46$；
$7.7 × 0.4 = 3.08$；
$7.7 + 0.4 = 8.1$；
$7.7 - 0.4 = 7.3$；
$1.5 × 0.5 = 0.75$；
$1.5 + 0.5 = 2$；
$1.5 - 0.5 = 1$；
$1.53 × 0 = 0$；
$1.53 + 0.07 = 1.6$；
$0.36 + 0.72 = 1.08$；
$0.72 - 0.36 = 0.36$；
$0.72 × 0.01 = 0.0072$；
$1.6 × 12.5 = 20$；
$1.6 + 12.5 = 14.1$；
$1.6 - 0.125 = 1.475$；
$1.6 × 0.001 = 0.0016$。

1. 得数保留一位小数。
$ 4.2×0.4\approx $1.7
$ 5.3×0.02\approx $0.1
$ 0.25×3\approx $0.8
$ 0.41×0.2\approx $0.1
$ 1.26×0.3\approx $0.4
$ 35×0.03\approx $1.1
$ 4.2×0.05\approx $0.2
$ 1.01×0.08\approx $0.1
2. 得数保留两位小数。
$ 0.14×0.09\approx $0.01
$ 0.07×0.6\approx $0.04
$ 2.32×0.03\approx $0.07
$ 4.33×0.02\approx $0.09
$ 0.75×0.06\approx $0.05
$ 12.8×0.02\approx $0.26
$ 0.37×0.5\approx $0.19
$ 4.13×0.3\approx $1.24
$ 3.14×0.08\approx $0.25
$ 5.27×0.5\approx $2.64
$ 0.45×0.04\approx $0.02

答案： 1. $4.2×0.4 = 1.68\approx1.7$
$5.3×0.02 = 0.106\approx0.1$
$0.25×3 = 0.75\approx0.8$
$0.41×0.2 = 0.082\approx0.1$
$1.26×0.3 = 0.378\approx0.4$
$35×0.03 = 1.05\approx1.1$
$4.2×0.05 = 0.21\approx0.2$
$1.01×0.08 = 0.0808\approx0.1$
2. $0.14×0.09 = 0.0126\approx0.01$
$0.07×0.6 = 0.042\approx0.04$
$2.32×0.03 = 0.0696\approx0.07$
$4.33×0.02 = 0.0866\approx0.09$
$0.75×0.06 = 0.045\approx0.05$
$12.8×0.02 = 0.256\approx0.26$
$0.37×0.5 = 0.185\approx0.19$
$4.13×0.3 = 1.239\approx1.24$
$3.14×0.08 = 0.2512\approx0.25$
$5.27×0.5 = 2.635\approx2.64$
$0.45×0.04 = 0.018\approx0.02$