In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
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Question: Most people see the world through _ types of visual-receptor cells.

Answer: four


Question: Cockatiels average _ to five eggs per nest, with an egg typically laid every other day.

Answer: four


Question: Carbohydrates contain four calories per gram while fat contains _ calories per gram.

Answer:
nine