Mary's parents decided to give her an allowance every Saturday. The first Saturday they gave her $.01. For each successive week, they double the amount given the previous week. If Mary saves her allowance, in how many weeks will she become a millionaire?

If you approach this using pennies, then $1 miilion = 100,000,000 pennies.

The amount of pennies received each week is , where i=0 for week 1, i=1 for week 2, etc. The sum of all pennies received in week i plus all previous weeks is:

.

So for the first few weeks you get:



etc.

To determine when she will be a millionaire you need to solve for :



Do you know how to solve for i?