Question 729333
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If you take 1 penny and double it each day for 31 days. 
How much money will you have? Express in $.
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        The other person gave the answer  2147483648  in his post.


        Without making any calculations, I see and I am convinced that his answer is  INCORRECT.


        How do I know it ?



<pre>
Very simple.  The answer is the sum

    1 + 2 + 4 + 8 + . . . + {{{2^30}}} = {{{2^31}}} - 1.


It is an odd number, while the other person provides an even number.


The  {{{highlight(highlight(true))}}}  answer is  {{{highlight(highlight(2147483647))}}}  cents, or  21,474,836.47 dollars.
</pre>

Solved correctly.