Question

计算下面各题，能简算的要用简便方法算．
0.75+1.25×2.4
5.67×0.21-0.62
3.8×6.7+3.3×3.8
1.28×0.29-0.29×0.28
101×4.8
4.89×99+4.89．

Answer 1

（1）0.75+1.25×2.4
=0.75+（1.25×8）×0.3
=0.75+10×0.3
=0.75+3
=3.75；

（2）5.67×0.21-0.62
=1.1907-0.62
=0.5707；

（3）3.8×6.7+3.3×3.8
=3.8×（6.7+3.3）
=3.8×10
=38；

（4）1.28×0.29-0.29×0.28
=0.29×（1.28-0.28）
=0.29×1
=0.29；

（5）101×4.8
=（100+1）×4.8
=100×4.8+4.8
=480+4.8
=484.8；

（6）4.89×99+4.89
=4.89×（99+1）
=4.89×100
=489．