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AR15.COM
7/18/2005 6:23:34 AM EDT
I have a question for mathematically inclined folks here…    

My boss sends out daily messages like the following.   Mostly, pretty generic stuff intended to “inspirational”.   Today I rec’d the following:

Thought of the Day

It is said that scientific knowledge is growing at an exponential rate.  To appreciate what that means, consider the story of a farmer who brought his horse to be shod and asked what it would cost.  The blacksmith said he would charge a penny for the first nail, 2 cents for the second, 4 cents for the third, and so on.  The farmer, innocent of mathematics, agreed.  For eight nails in each shoe, or 32 nails altogether, his bill came to $42,949,672.95.

An exponential rate of growth is a fearsome thing.

-From "Bits and Pieces"


For kicks, I decided to “do the math” on my desk calculator.  When I do the calculation, doubling each number to get the next, I calculate the total to be $21,474,836.48.  It appears that the $42,949,672.95 figure is the result of 33 “nail” calculations, not 32.  Did I calculate the problem incorrectly?  Is this really an “exponential” calculation?    Thanks!
7/18/2005 6:33:34 AM EDT
[#1]
you just doubled the numbers, did you add up all the previously doubled numbers, e.g. 1+2+4+8+16+...?
7/18/2005 6:38:38 AM EDT
[#2]

Quoted:
you just doubled the numbers, did you add up all the previously doubled numbers, e.g. 1+2+4+8+16+...?



No, I didn't do that... that is probably why I came up with a different result.  When/if our system comes back online, I'll try to do this on Excel so I don't have to add up all the numbers.   Thanks!
7/18/2005 6:51:27 AM EDT
[#3]
I used excel and got 42949672.95



edit:

0.01
0.02
0.04
0.08
0.16
0.32
0.64
1.28
2.56
5.12
10.24
20.48
40.96
81.92
163.84
327.68
655.36
1310.72
2621.44
5242.88
10485.76
20971.52
41943.04
83886.08
167772.16
335544.32
671088.64
1342177.28
2684354.56
5368709.12
10737418.24
21474836.48
(sum) $42,949,672.95
7/18/2005 6:56:07 AM EDT
[#4]
..."Afterwards, the farmer kicked the blacksmith's ass and left ten bucks on the counter".