The answer is: " 100 cultures " .
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Take the number of the day we are at (from the beginning; in this case, "9" (for "Day 9").
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Then add "1" to that number (in this case, " 9 + 1 = 10" .
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Then, take that value (in this case, "10"); and "square" that value ; (in this case; " 10² = 10 * 10 = 100 . This is the answer.
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The answer is: " 100 cultures " .
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Note: We get this steps by noticing the trend from the information provided.
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