In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
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Question: Dingoes live to _ or six years of age in the wild and fifteen years in captivity.

Answer: five


Question: Humans brains are about _ times bigger than in chimpanzees.

Answer: three


Question: European cities tend to have population densities more than _ times that of U.S. urban areas.

Answer:
four