Which would you rather have, one million dollars or the amount of money you would get if a penny was doubled every day for a (30-day) month?
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"if a penny was doubled" is not clear. There's no way to double a penny.
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If you receive a penny the 1st day, then 2 pennies the 2nd day, that's 3 pennies.
Day Pennies
1 1
2 3
3 7
4 15
5 31
6 63
If that's the case, in 30 days you have 2^30-1 = 1,073,741,823 pennies.
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If the total amount is doubled each day, then you have 2 pennies the 2nd day, not 3. In 30 days you have 2^29 pennies = 536,870,912 pennies.
Day Pennies
1 1
2 2
3 4
4 8
5 16
6 32