Title
I want to be a millionaire!
Problem Statement
If I put $1.00 in the bank, how many years would it take for me to become a
millionaire if my money doubled each year?
Problem setup
This problem involves using the power
of exponents.
Plans to Solve/Investigate the
Problem
We guessed some different
possibilities for this. We then decided to put numbers into an Excel spreadsheet
with 3 columns labeled Year, $ and Powers.
Investigation/Exploration of the
Problem
The first number in the "Year" column
is 1 for the first year and for every year thereafter, the A rows are labeled up
to 21. The first number in the "$" column is 1 for the one dollar I put in the
bank the first year. The first power in the "Powers" column is 1 because in the
first year my $1.00 is just one dollar or one to the first power. We put the
following formula in cell B3: =B2*2. We used the black plus cursor to drag the
column down so that Excel could calculate the money for each year. We put the
following formula in cell C2: =2^(A21). The same procedure for using the black
plus and dragging down is used for this formula for Excel to calculate the
values. The numbers in the "$" column and the "Powers" column should be
the same. The spreadsheet is as follows:
Year 
$ 
Powers 
1 
1 
1 
2 
2 
2 
3 
4 
4 
4 
8 
8 
5 
16 
16 
6 
32 
32 
7 
64 
64 
8 
128 
128 
9 
256 
256 
10 
512 
512 
11 
1024 
1024 
12 
2048 
2048 
13 
4096 
4096 
14 
8192 
8192 
15 
16384 
16384 
16 
32768 
32768 
17 
65536 
65536 
18 
131072 
131072 
19 
262144 
262144 
20 
524288 
524288 
21 
1048576 
1048576 
Extensions of the Problem
An extension of this problem was the
following: If I want to be a millionaire in ten years, how much will my initial
deposit in the bank have to be if my money doubled each year? We guessed various
numbers and plugged them into Excel using the same formulas. The amount of money
needed initially is $1954.00.
Author & Contact
Pam Joseph
mailto:prj1@aol.com
Link(s) to resources, references, lesson plans, and/or other
materials
Link 1
Link 2
