第三页：
六、解决问题。
1. 680÷4×3.2=170×3.2=544(千米)
2. ① 541.8÷15= 36.12(米)
② 541.8÷7= 77.4 (米)
③ 77.4-36.12=41.28 (米)
3.185×5.4= 999(千米)
4.0.8×24×18=19.2×18=345.6(元)
第四页：
5.324×1.2+48=388.8+48=436.8(元)
提高篇：
1.28
2. 392.6×192-39260×0.927.5×23+31×2.5
=392.6×192-392.6×92=2.5×(3×23)+31×2.5
=392.6×(192-92)=2.5×(69+31)
=392.6×100 =2.5×100
=39260=250
3. 0.79×0.46+7.9×0.24+11.4×0.079
=0.79×0.46+0.79×2.4+1.14×0.79
=0.79×(0.46+2.4+1.14)
=0.79×4
