7.42×99+7.42 =7.42×(99+1)=7.42×100=7421.5×102=1.5×(100+2)=1.5×100+1.5×2=150+3=153 3.5×101－3.5 =3.5×(101-1)=3.5×100=35012.5×8.8 =12.5×8×1.1=100×1.1=110 12.5×2.7×8=12.5×8×2.7=100×.7=...