Simon deposited an amount of $$6,500$ in an account that accumulated at $14\mathrm{.}25\%,$ compounded monthly for $4\mathrm{.}5$ years, after which he added an additional deposit of $$1,250,$ and followed by another deposit of $$850$ a year after that. How much will he have accumulated after a total of $8$ years? $($S marks$)$t