If a car has value V and depreciates at a% per year (so a/100) then after one year its value has lowered by V(a/1000)= aV/100 so is now V- aV/100=(100V- aV)/100A= [(100- a)/100]V. That is, V has been multiplied by (100- a)/100. The second year, the same thing happens- its value, now [(100- a)/100]V, is again multiplied by (100- a)/100 so after the second year the value is [(100- a)/100]^2V.
The third you again multiply by (100- a)/100. What will the value be after the third year? The fourth year? Get the point?