It depends how the compounding is done, and how the interest is quoted.
{under some regulations, the rate quoted will be the annual percentage rate,
rather than the nominal rate, so it might be as simple as =90000*(1+8.5%).
If the interest per month is 8.5% divided by 12, and the interest is
compounded monthly, you'd end up with =90000*(1+8.5%/12)^12