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

[Q]: Mice are fertile animals because female mice come into heat every _ to five days.
[A]: four


[Q]: Acrobats mount a single bicycle until _ people in all are stacked on top of it.
[A]: ten


[Q]: Infertility affects as many as _ percent of American couples.
[A]:
ten