0.35×1.25×2×0.8 =(0.35×2)×(1.25×0.8) =0.7×1 =0.7 (乘法分配律) 2.5×2.4 =2.5×4×0.6 =10×0.6 =6 (拆数,乘法结合律) 32.4×0.9+0.1×32.4 =32.4×(0.9+0.1) =32.4×1 =32.4 (乘法交换律和乘法结合律) 12.5×0.96×0.8 =12.5×0.8×0.96 =10×0.96 =9.6 (乘法分配律)