My retirement fund [Australian Superannuation fund] can be checked at any time. The fund invests in shares, which can go up - or down. Money is going IN regularly [monthly].
At any given time, how do I calculate the interest rate? I think this becomes a Compound interest calculation, but I'm not sure if I should specify calculating interest daily, weekly, or other.
I've found a few calculators for determining a final value based on a compound interest rate: I'm still looking for how to calculate the rate when given the final value.
Edit: I found formulas for Compound Interest, and Regular Deposits, here. For deposits, the site states that interest "can't be solved for algebraically, and must be found numerically." That makes for fun.