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三、列竖式计算。
1. $50.6×4.3 =$
2. $4.08×2.5 =$
1. $50.6×4.3 =$
2. $4.08×2.5 =$
答案
1. $50.6×4.3 = 217.58$
2. $4.08×2.5 = 10.2$
四、脱式计算。（能简算的要简算）
$5.15×3.7 + 6.3×5.15$
$49.6 - 8.5×1.1$
$5.15×3.7 + 6.3×5.15$
$49.6 - 8.5×1.1$
答案
1. 51.5
2. 40.25
2. 40.25
五、解决问题。
四（1）班共有45名同学，如果每人回收1.5千克废纸，每千克废纸可生产0.8千克再生纸。四（1）班同学回收的废纸一共可以生产多少千克再生纸？
四（1）班共有45名同学，如果每人回收1.5千克废纸，每千克废纸可生产0.8千克再生纸。四（1）班同学回收的废纸一共可以生产多少千克再生纸？
答案
$45 × 1.5 × 0.8=54$（千克）
算一算
0.96 - 0.32 =
8.65 - 6.31 =
7.82 - 7.21 =
0.78 - 0.24 =
1 - 0.55 =
8.34 - 6.22 =
8.97 - 6.9 =
20.54 - 8.4 =
1.78 - 0.5 =
0.79 - 0.6 =
0.96 - 0.32 =
8.65 - 6.31 =
7.82 - 7.21 =
0.78 - 0.24 =
1 - 0.55 =
8.34 - 6.22 =
8.97 - 6.9 =
20.54 - 8.4 =
1.78 - 0.5 =
0.79 - 0.6 =
答案
0.96 - 0.32 = 0.64
8.65 - 6.31 = 2.34
7.82 - 7.21 = 0.61
0.78 - 0.24 = 0.54
1 - 0.55 = 0.45
8.34 - 6.22 = 2.12
8.97 - 6.9 = 2.07
20.54 - 8.4 = 12.14
1.78 - 0.5 = 1.28
0.79 - 0.6 = 0.19
8.65 - 6.31 = 2.34
7.82 - 7.21 = 0.61
0.78 - 0.24 = 0.54
1 - 0.55 = 0.45
8.34 - 6.22 = 2.12
8.97 - 6.9 = 2.07
20.54 - 8.4 = 12.14
1.78 - 0.5 = 1.28
0.79 - 0.6 = 0.19
