According to financial planners, the average retiree requires approximately $70\%$ of their last year's working salary each year to live comfortably in retirement. Assume that you want to earn a fixed amount of interest each year in retirement. Your goal is to spend only the interest and still live comfortably; thus, you will be able to spend the same amount of money each year forever. Assume you retire at age $66$ and can earn a $6\%$ return on your retirement savings. How much must you have saved to live only off the interest?

Suppose you live through age $90.$ How much money will you be able to bequeath $($i$.$e$.$ pass on in your will$)?$