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

[Q]: Prostate cancer is categorized in _ stages.
[A]: four


[Q]: Liquids usually descend in three to five seconds, and solids in _ to twenty seconds.
[A]: eight


[Q]: Quanta has _ mass and takes up no space, yet extends out into the universe.
[A]:
no