第一单元练习三1.在下面的中填上适当的数。59×2.5×0.4=×（×）7.8×15+2.2×15=(+)×150.02×1.25×5×8=(×)×(×)2.把左右两边相等的式子用线连起来。(5+8)×0.4 9×5+9×1.64.6×19+5.4×19 5×0.4+8×0.49×(5+1.6) (4.6+5.4)×193.6×4×2.5 3.6×(4×2.5)3.用简便方法计算下面各题。2.5×(3.8×0.04) 7.69×10146×0.33+54×0.330.125×72答案提示1.59 2.5 0.4 7.8 2.2 0.02 5 1.25 8 2.3. 2.5×(3.8×0.04) =2.5×0.04×3.8 =0.1×3.8 =0.38 7.69×101=7.69×(100+1)=776.69 46×0.33+54×0.33=(46+54)×0.33=100×0.33=33 0.125×72=0.125×8×9=1×9=9