Puzzle of the Week on 3/2/02
  rollover
 
   
Sally and Sam are 12 year old twins. Their parents are very wealthy. On March 1, the parents gave their children a choice of two ways to receive their March allowance.
One choice was to receive $100 each day for the month of March.
The other choice was to receive one penny on March 1. The next day (March 2), the penny would be doubled. The next day (March 3), the two pennies from March 2 would be doubled. Continue this pattern until March 31.
Sam chose $100 each day for the entire month of March.
Sally chose to receive the penny on March 1 and double her amount every day all through the month.

By March 31, which of the twins received the most allowance, and how much more?
The solution
Sam received $100 each day for 31 days.
Multiply $100 x 31 = $3100
Here are Sally's figures:
March 1
$0.01
March 2
$0.02
March 3
$0.04
March 4
$0.08
March 5
$0.16
March 6
$0.32
March 7
$0.64
March 8
$1.28
March 9
$2.56
March 10
$5.12
March 11
$10.24
March 12
$20.48
March 13
$40.96
March 14
$81.92
March 15
$163.84
March 16
$327.68
March 17
$655.36
March 18
$1,310.72
March 19
$2,621.44
March 20
$5,242.88
March 21
$10,485.76
March 22
$20,971.52
March 23
$41,943.04
March 24
$83,886.08
March 25
$167,772.16
March 26
$335,544.32
March 27
$671,088.64
March 28
$1,342,177.28
March 29
$2,684,354.56
March 30
$5,368,709.12
March 31
$10,737,418.24
Sally's Total  
$21,474,836.47

Subtract Sam's total from Sally's total:
$21,474,836.47 - $3100 = $21,471,736.47
Sally received the most allowance for the month of March!
  Home   |   Programs    |   Puzzle of the Week    |  
 
If you can't access your e-mail from a web page link, you may copy and paste (or type):