For example How many months will $100,000 invested at 8% last if I withdraw $1,000 each month?If you have Excel, there is a function:=NPER((8/12)%,-1000,100000)8/12% is the monthly interest rate-1000 is the monthly withdrawal100000 is the starting amountAnswer is: 165.3405411 monthsDivide that by 12 to get 13.77837843 yearsHowever, I want to emphasize that this will be correct only if the interest