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.

Q: Echinoderms have radial symmetry , many having ____ or multiples of five arms.

A: five
****
Q: Most butterflies live only two to ____ weeks.

A: four
****
Q: Many scientists believe that, sometime around ____ billion years ago, simple life arose.

A:
four
****