计算下面各题．（怎样简便怎样算）0.68×40.5×0.762.4×15-66.95÷6512.5×25×0.325.8×2.8+2.8+3.2×2.8．

Question

计算下面各题．（怎样简便怎样算）
0.68×40.5×0.7
62.4×15-66.95÷65
12.5×25×0.32      
5.8×2.8+2.8+3.2×2.8．

Answer 1

①0.68×40.5×0.7
=（40.5×0.2）×（3.4×0.7）
=8.1×2.38
=（8+0.1）×2.38
=8×2.38+0.1×2.38
=19.04+0.238
=19.278

②62.4×15-66.95÷65
=936-1.03
=934.97

③12.5×25×0.32  
=（12.5×8）×（25×0.04）
=100×1
=100
    
④5.8×2.8+2.8+3.2×2.8
=2.8×（5.8+3.2）
=2.8×9
=25.2