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.

Neutrons consist of one up quark and ____ down quarks.
two

Cognitive therapy is a time-limited treatment lasting ____ to four months.
three

Luminosity decreases by almost four orders of magnitude in approximately ____ million years.

five