2026年经纶学典5星学霸五年级数学上册人教版第20页答案
链接“7星学霸”第8辑第4讲
1. 计算:2.009×43+20.09×2.9+200.9×0.28。

答案

1.
2.009×43+20.09×2.9+200.9×0.28
=20.09×4.3+20.09×2.9+20.09×2.8
=20.09×(4.3+2.9+2.8)
=20.09×10
= 200.9
2. 计算:4.23×7.12+42.3×0.398-0.423×11。

答案

2.
4.23×7.12+42.3×0.398-0.423×11
=4.23×7.12+4.23×3.98-4.23×1.1
=4.23×(7.12+3.98-1.1)
= 4.23×10
=42.3
3. 计算:$7.816×1.45+3.14×2.184+0.169×78.16$。

答案

3.
7.816×1.45+3.14×2.184+0.169×78.16
=7.816×(1.45+1.69)+3.14×2.184
=7.816×3.14+3.14×2.184
=3.14×(7.816+2.184)
= 3.14×10
=31.4
4. 计算:$314×0.45+62.8×2.6+9.42$。

答案

4.
314×0.45+62.8×2.6+9.42
=31.4×4.5+31.4×2×2.6+31.4×0.3
=31.4×4.5+31.4×5.2+31.4×0.3
=31.4×(4.5+5.2+0.3)
= 31.4×10
=314
5. 计算:18.9×178.178+0.94−17.8×189.189。

答案

5.
18.9×178.178+0.94−17.8×189.189
=18.9×178×1.001+0.94−17.8×189×1.001
=(18.9×178×1.001−178×18.9×1.001)+0.94
=0+0.94
=0.94
6. 计算:3.85×65+12.5×0.5+51×3.5。

答案

6.
3.85×65+12.5×0.5+51×3.5
=3.85×65+5.1×35+1.25×5
=3.85×65+(3.85+1.25)×35+1.25×5
=3.85×65+3.85×35+1.25×35+1.25×5
=3.85×(65+35)+1.25×(35+5)
= 385+50
=435