If your allowance was a penny doubled every day, how many days would it take for you to have over $1000.00? $10,000.00? How much money would you have on the 15th day?
On the 15th day you would have $327.68 - this is done by doing 1*2¹⁵. On the 17th day you would have $1310.72 and on the 20th day you would have $10,485.76