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.

Object permanence is seen in children ____ to twelve months old .
eight

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

Geraniums usually require additional fertilizer during the growing season every four to ____ weeks.

six