Basic Interest Formulas


Simple Int.    I = P*r*t    Accumulation   A = P*(1+r*t)  
 Compound Int.  Accumulation A = P*(1+i)^n  
                                       Compound Interest present value   P = A*(1+i)^(-n)
                                        Effective rate (compound)    r[eff] = (1+r/m)^m-1      
 Annuity                   sum     S = R*((1+i)^n-1)/i        

                                        present value.    P = R*(1-(1+i)^(-n))/i              Read the signs carefully!