Question

A leprechaun places a magic penny under a​ girl's pillow. The next night there are 2 magic pennies under her pillow. Each night the number of magic pennies doubles. How much money will the girl have after 22 ​nights?

Answer 1

• tn = 2097152 pennies
• tn = 20971.52 dollars.

Explanation:

A surprisingly large amount of money.

The question is "Does the amount of money just double or do the previous amounts add to the present amount?"

I think it just doubles. Not only that, but she can't spend any of it until night 22 is reached.

• tn = a*2^(n - 1)
• a = 1 She starts with 1 penny.
• n = 22
• tn = 1*2^(22 - 1)
• tn = 1*2^21
• tn = 2097152 pennies
• tn = 20971.52 dollars.