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.

Cats have five toes on their front paws, but only ____ touch the ground when walking.
four

Tuataras reproduce very slowly, sometimes taking ____ years to reach sexual maturity.
ten

Fingernails grow out in ____ months, toenails in a year.

six