Let's let P be our initial Principal.

After 1 month, our compound period, P has accrued interest. Your balance is now P*(1 + .0485/12).

After another month, Your balance would be (P*(1+.0485/12))*(1+.0485).

Simplifying, this would be, after 2 months, P*(1+.0485/12)^2

After 3 months, P*(1+.0485/12)^3

After 4 months, P*(1+.0485/12)^4

If it does this for 6 years, or 72 months, then it will be P(1+.0485/12)^72. We set this equal to $325,000 and solve for P:

P = ($325000)/((1+.0485/12)^72)

P = $243085.19