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If you buy something and sell it later on the same day, how do you calculate 'investment'?
Your initial investment in this case is $9 on the first morning. Every other morning you are using part of your profits to buy the new piece of jewelry, so you are actually not investing any new funds. So each day you are effectively keeping $1 of your profits and re_re-investing $9. But your initial investment of your own funds is only the first $9. In other words if you only had $9 in the bank at the start of the year you could make $365 profits during the year and finish up with $374 in the the bank at the end of the year.