8.9÷0.125÷0.8 =8.9÷(0.125×0.8) =8.9÷0.1 =89 8.7×9.9 =8.7×(10-0.1) =8.7×10-8.7×0.1 =87-0.87 =86.13 7.2÷0.25÷0.4 =7.2÷(0.25×0.4) =7.2÷0.1 =72 1.7×1.4+8.3×1.4 =(1.7+8.3)×1.4 =10×1.4