Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.

Harpists spend ninety percent of their lives tuning their harps and ____ percent playing out of tune.
ten

Acupuncture needles are about two to ____ inches long.
three

Most babies eat every two to ____ hours.

four