①4.8×0.25=1.2×(4×0.25)=1.2×1=1.2②2.33×0.5×4=2.33×(0.5×4)=2.33×2=4.66③1.5×105=1.5×(100+5)=1.5×100+1.5×5=150+7.5=157.5④1.2×2.5+0.8×2.5=(1.2+0.8)×2.5=2×2.5=5.