Question 590908
You recieve a penny on January 1st, two cents the next day, four cents the next and so on,doubling every day. How long will it take to be a millionaire?
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The total each day is {{{2^d - 1}}} cents.
$1,000,000 = 100,000,000 cents.
{{{2^d - 1 = 100000000}}}
{{{2^d = 99999999}}}
d*log(2) = log(99999999}
d = log(99999999)/log(2)
d =~ 26.575 days
--> 26 days
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 Suppose you started with a nickle and doubled, how long before you were worth a million dollars?
$1,000,000 = 100,000,000 cents = 20,000,000 nickels
Amt = {{{5*(2^d - 1) = 100000000}}} 
{{{2^d - 1 = 20000000}}}
{{{2^d = 19999999}}}
d*log(2) = log(19999999}
d = log(19999999)/log(2)
d =~ 24.25 days
--> 25 days
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Not much difference.  If you multiply by 5 each day, it was reduce the time more drastically.