QoD: Would you rather have $1,000,000 or start with a penny and double your money every day for 30 days?

Oct 08, 2019
Question of the Day, Savings, Compound Interest, Investing

Good question to show the power of compounding...of course be sure to tell them that no investment would double on a daily basis for 30 days;) Calculators not allowed! 

Answer: Starting with a penny and doubling it every day compounds to $10.7 million after 30 days

Day 1: You would have $0.02

Day 2: You would have $0.04

Day 3: You would have $0.08

Day 4: You would have $0.16...

Day 30: You would have $10,737,418.24.


  • How much would the penny have grown to on Day 29? How much did the value increase between Day 29 and Day 30? 
  • Now apply this concept to your own savings..is it better to start saving early (e.g., starting at age 20 and saving for 30 years) or waiting until your life is more stable (start saving at age 30 and saving for 20 years). Use the example of the penny doubling to explain your answer. 

Here's the ready-to-go slides for this Question of the Day that you can use in your classroom.

Behind the numbers:

Here's the spreadsheet with the calculations. 


Looking for more ways to show the power of compounding? We have a printable infographic explaining compound interest (along with 3 others) that are available here



About the Author

Tim Ranzetta

Tim's saving habits started at seven when a neighbor with a broken hip gave him a dog walking job. Her recovery, which took almost a year, resulted in Tim getting to know the bank tellers quite well (and accumulating a savings account balance of over $300!). His recent entrepreneurial adventures have included driving a shredding truck, analyzing executive compensation packages for Fortune 500 companies and helping families make better college financing decisions. After volunteering in 2010 to create and teach a personal finance program at Eastside College Prep in East Palo Alto, Tim saw firsthand the impact of an engaging and activity-based curriculum, which inspired him to start a new non-profit, Next Gen Personal Finance.