DaysInYear = 366
InterestRate = 215
DayBalanceSum = 0
for each Day in Year
DayBalanceSum += Day.Balance
InterestRaw = DayBalanceSum * InterestRate
InterestRaw += DaysInYear * 5000
Interest = InterestRaw / (DaysInYear * 10000)
Balance += Interest
> In computing, a fixed-point number representation is a real data type for a number that has a fixed number of digits after (and sometimes also before) the radix point.
> A value of a fixed-point data type is essentially an integer that is scaled by an implicit specific factor determined by the type.
But that practically holds only for a reasonable amount of simple arithmetics. Fractional components tend to grow exponential for many numerical methods repeated multiple times. This can happen if you're describing money and want to apply a complex numerical method from an economics article for whatever purpose. Might be worth it but be careful not to carry ever expanding fractions in your system.
If you are running an economic simulation you generally don't have to worry about rounding, the whole thing is only approximate anyway.
I wish I could up vote you more than once. You are bang on.