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For a month with 31 days option three would be obviously the best option because on day 11 you would already be getting 1024p.
If it is only for eight days, option 1 would be the best as 8 times 10 is £80 for option 2 would be £38 and option 3 £25.5. So the best option would be option 1 for eight days. For how long you will take to be a millionaire with option three the answer is 28 days as it is 1p+2^27p which is £1342177.29. Option 1 would always be better than option 2 and the most fruitful day for option 3 is the last day of the month.

With help from Maggie (age 12, from Takapuna Normal Intermediate School)