(1)2.5×8×0.4×0.125=(2.5×0.4)×(8×0.125)=1×1=1(2)0.88×4.9+5.1×0.88=0.88×(4.9+5.1)=0.88×10=8.8(3)7.9÷12.5÷0.8=7.9÷(12.5×0.8)=7.9÷10=0.79(4)9.1-1.2÷6-6.24=9.1-0.2-6.24=2.66