I have two questions:
How can I calculate compound interest when I want to reinvest a percentage of the sum of my principal and interest periodically?
To make it clearer,
Usually I use this formula for calculating compound interest: $M = P( 1 + i )^n$.
This time I want to compound only a percentage of the sum of the principal and interest
This is what I am looking at:
I invest $1000$ for a month, at the end of the month I get $1100$ (principal plus interest), and I want to re-invest $60%$ of the total amount for $n$ periods.
I want to compound the interest on the principal daily till the investment matures, i.e. if am investing for one year, I want the daily interest to be compounded to the principal.