In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[Q]: Most children recover from croup in _ to five days.
[A]: three


[Q]: Most smokers try to quit at least _ or six times before they succeed, researchers say.
[A]: five


[Q]: Univalves have _ shell, and bivalves have two shells.
[A]:
one