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.

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

Potential energy is divided into ____ different types of energy.
three

Ground squirrels breed once a year, averaging ____ to eight per litter.

seven