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.

Most healthy men experience about three to ____ erections in their sleep each night.
five

World population continues to rise, even as a few countries move toward ____ growth.
zero

Scorpions are ____ legged venomous arachnids .

eight