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.

Irrigation can increase land productivity by three to ____ times, especially in the north.
seven

Blisters normally burst and crust over within three to ____ days.
five

Smoking is the single most preventable cause of mortality, responsible for one in every ____ deaths.

six