A Penny Doubled For 30 Days

A lot of people have asked this question; what is one penny doubled for 30 days. When I first heard of this question it made me think of something I watched a long time ago on TV. about rice. I looked up the story and it is about a selfish raja, a king in India, who demanded most of the rice from his kingdom. After a famine hit and most people were left hungry the raja would not part with his mass amounts of rice.

After a good deed done by one of the villagers the raja ordered that she be rewarded. She asked for one grain of rice and for it to be doubled for 30 days. He granted this to her not thinking it would add up to a lot. By the 30th day he had given to her all his rice. She gave most of the rice to her fellow starving villagers and then gave the raja some rice back. The raja was happy and learned his lesson about giving. He lived the rest of his days being fair to the people in his kingdom.
That is a brief summary of the story.

It has been told time and time again with different people and in different setting. Another spin off story from this one that I remember is when a boy gets rewarded. He asks for a grain a rice to be put on a checkered board and as it moved from square to square it would double until he reached the end. Both stories have the same idea.

So what really is a penny doubled for 30 days?

• Day 1: $0.01 x 2 = $0.02
• Day 2: $0.02 x 2 = $0.04
• Day 3: $0.04 x 2 = $0.08
• Day 4: $0.08 x 2 = $0.16
• Day 5: $0.16 x 2 = $0.32
• Day 6: $0.32 x 2 = $0.64
• Day 7: $0.64 x 2 = $1.28
• Day 8: $1.28 x 2 = $2.56
• Day 9: $2.56 x 2 = $5.12
• Day 10: $5.12 x 2 = $10.24
• Day 11: $10.24 x 2 = $20.48
• Day 12: $20.48 x 2 = $40.96
• Day 13: $40.96 x 2 = $81.92
• Day 14: $81.92 x 2 = $163.84
• Day 15: $163.84 x 2 = $327.68
• Day 16: $327.68 x 2 = $655.36
• Day 17: $655.36 x 2 = $1,310.72
• Day 18: $1,310.72 x 2 = $2,621.44
• Day 19: $2,621.44 x 2 = $5,242.88
• Day 20: $5,242.88 x 2 = $10,485.76
• Day 21: $10,485.76 x 2 = $20,971.52
• Day 22: $20,971.52 x 2 = $41,943.04
• Day 23: $41,943.04 x 2 = $83,886.08
• Day 24: $83,886.08 x 2 = $167,772.16
• Day 25: $167,772.16 x 2 = $335,544.32
• Day 26: $335,544.32 x 2 = $671,088.64
• Day 27: $671,088.64 x 2 = $1,342,177.28
• Day 28: $1,342,177.28 x 2 = $2,684,354.56
• Day 29: $2,684,354.56 x 2 = $5,368,709.12
• Day 30: $5,368,709.12 x 2 = $10,737,418.24

Over 10 million dollars! That is a lot of money. 

This is a classic example of how compound interest (interest earned from your interest) can make your money grow exponentially over time. Of course no one is going to give you this kind of interest. 

There is a way to see how long it would take to double your money at a certain interest rate. You can use the Rule of 72. Simply divide 72 by the interest rate to get the number of years. For example, if you invest $100 at 6% interest, it will take about 12 years to double your money (72 / 6 = 12). If you invest $100 at 12% interest, it will take only 6 years to double your money (72 / 12 = 6).

I hope that this question, what is a penny doubled for 30 day is just a curiosity and not the beginning of trying to save money. Even billionaires could only do this for a short period of time. Below I have savings chart for you.  There are 52 entries, one for each week of the year. Every week choose an amount to save and cross it off the list. At the end of the year, or at the end of 52 weeks (you don’t need to wait for the beginning of the year), you will have saved $1,000. 

 Money Savings Chart

I have included a PDF version that you can download and keep in a binder, on the refrigerator or wherever is the most convenient place for you. Download it here → Money Savings Chart