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.
One example: Female snakes incubate eggs inside of their bodies, giving birth to live young of ____ or more.
Solution is here: ten
Explanation: Snakes give birth to minimum ten young ones so ten is a correct answer.

Now, solve this: Modern technology makes it possible to examine and treat infants even under ____ months of age.
Solution:
six