《2025年口算训练五年级数学上册人教版双色升级版》

$1.8×3=$5.4
$18×3=$54
$1.8×0.3=$0.54
$0.25×4=$1
$2.5×4=$10
$25×4=$100
$0.9×0.01=$0.009
$0.2×0.04=$0.008
$0.45×0.01=$0.0045
$29×0.03=$0.87
$0.18×0.5=$0.09
$0.15×0.4=$0.06
$0.35×0.3=$0.105
$5×0.05=$0.25
$8×0.09=$0.72
$12×0.05=$0.6
$4.9×0.01=$0.049
$4.35×0=$0
$9×1.34=$12.06
$0.19×0.05=$0.0095
$5.8×0.05=$0.29

答案： 解析：这些题目都是基础的乘法口算题，涉及到小数与整数、小数与小数的乘法运算。根据乘法运算法则，可以直接计算出结果。
答案：
$1.8×3=5.4$
$18×3=54$
$1.8×0.3=0.54$
$0.25×4=1$
$2.5×4=10$
$25×4=100$
$0.9×0.01=0.009$
$0.2×0.04=0.008$
$0.45×0.01=0.0045$
$29×0.03=0.87$
$0.18×0.5=0.09$
$0.15×0.4=0.06$
$0.35×0.3=0.105$
$5×0.05=0.25$
$8×0.09=0.72$
$12×0.05=0.6$
$4.9×0.01=0.049$
$4.35×0=0$
$9×1.34=12.06$
$0.19×0.05=0.0095$
$5.8×0.05=0.29$

1. 得数保留一位小数。
$1.25×0.5\approx $0.6
$0.32×0.3\approx $0.1
$0.2×2.3\approx $0.5
$3.6×0.03\approx $0.1
$0.46×0.2\approx $0.1
$1.3×0.4\approx $0.5
$2.51×3\approx $7.5
$3.3×0.5\approx $1.7
$1.7×0.4\approx $0.7
$2.7×0.3\approx $0.8
2. 得数保留两位小数。
$0.45×0.1\approx $0.05
$1.2×0.08\approx $0.10
$0.125×0.3\approx $0.04
$0.29×0.8\approx $0.23
$7.2×0.03\approx $0.22
$0.32×0.05\approx $0.02
$3.125×0.5\approx $1.56
$41.2×0.04\approx $1.65
$50.8×0.06\approx $3.05

答案： 1. $1.25×0.5=0.625\approx0.6$
$0.32×0.3=0.096\approx0.1$
$0.2×2.3=0.46\approx0.5$
$3.6×0.03=0.108\approx0.1$
$0.46×0.2=0.092\approx0.1$
$1.3×0.4=0.52\approx0.5$
$2.51×3=7.53\approx7.5$
$3.3×0.5=1.65\approx1.7$
$1.7×0.4=0.68\approx0.7$
$2.7×0.3=0.81\approx0.8$
2. $0.45×0.1=0.045\approx0.05$
$1.2×0.08=0.096\approx0.10$
$0.125×0.3=0.0375\approx0.04$
$0.29×0.8=0.232\approx0.23$
$7.2×0.03=0.216\approx0.22$
$0.32×0.05=0.016\approx0.02$
$3.125×0.5=1.5625\approx1.56$
$41.2×0.04=1.648\approx1.65$
$50.8×0.06=3.048\approx3.05$