Compound Interest - Present Value. Camila is 35 years old now and she believes she needs $1,150,000.00 when she retires at 65. If her portfolio can get her a return of 9.73% compounded weekly, how much should she invest today (round to nearest the cent)? Compound Interest - Present Value. Archer is 25 years old now and he believes he needs $900,000.00 when he retires at 60. If his portfolio can get him a return of 11.11% compounded semi-annually, how much should he invest today (round to nearest the cent)?